What is Msmpeng.exe and How to Remove It

Has your processor been at 100% utilization lately? If you went to the Task Manager in Windows and looked at your processes tab, you may have noticed a process called msmpeng.exe eating up all your available CPU.

So what is msmpeng.exe and how can you prevent it from slowing your system down? Well, unlike what you may have read elsewhere, it is not spyware or malware. It’s actually quite ironic because it’s associated with Windows Defender, the anti-spyware product from Microsoft.

Unfortunately, this crappy piece of software is already installed on Windows Vista and it also comes with Windows Live One Care. There are two ways to stop msmpeng.exe from using system resources: exclude the Windows Defender directory from scanning or simply turn off Windows Defender.

Exclude directory for scanning

If you would like to keep using Windows Defender, then your only chance of fixing the high processor usage issue is to prevent the Windows Defender directory from being scanned.

Apparently, the service scans it’s self and therefore eats up all the CPU. Open Windows Defender, click on Tools and then Options. Now scroll down to the Advanced Options section:

windows defender options

Now click on the add button under the “Do not scan these files or locations” section. Now type in the path for the Windows Defender directory:

c:\program files\windows defender

Click OK and now make sure to click the Save button. Hopefully this will fix your high CPU usage error with Windows Defender. Also be sure to read my post on how to customize all the options for Windows Defender like what stuff to monitor in real-time, etc.

Turn off Windows Defender

The other option is to simply turn off Windows Defender, which I think is a better idea anyway. There are lots of other spyware programs out there that are much better than Windows Defender.

To turn off Windows Defender, open the program and click on Options. Now go to Administrator options and uncheck the Use Windows Defender box. Make sure to click Save.

what is msmpeng[5]


So that’s it! msmpeng should now no longer be messing up your system. If you’re still having troubles, post a comment here. Enjoy!

Comments [72]

  1. How do I stop it through OneCare?

  2. My CPU was eating(?) my computer all the time. Just followed your advice and CPU is now using 2% instead of 98%.


  3. I liked this usefull information.

    You wrote; the other option is to simply turn off Windows Defender, which I think is a better idea anyway. There are lots of other spyware programs out there that are much better than Windows Defender.

    Which spyware programs are you talking about…if I'm using them then I'll want to turn off windows defender, too.

    Thanks. Mike

  4. Thanks. This msmpeng.exe process was slowing the pc down to a crawl. Merry Christmas and Happy New Year.

  5. I have Windows Defender uninstalled (WinXP) and msmpeng.exe is still gobbling up resources. Could MSE (Microsoft Security Essentials) be using the service instead? Can it just be turned off in msconfig?

  6. If disabling like mentioned above doesnt work try win+r, services.msc, ok, then disable the windows defender services from the list.

  7. Thanks! went from 100% CPU usage down to 12 – thanks again.

  8. Microsoft Forefront Client Security has this problem, as well. I adjusted your instructions, and using the Forefront settings, excluded the directory within the Forefront program folder that has MsMpEng.exe in it.

    Thanks so much for your post. The suggestions on a number of other pages did not help me at all.

  9. Thanks for this article! I was wondering what msmpeng.exe was and why it was eating up all my CPU cycles!

  10. I'm running WindowsXP with Microsoft Security Essentials and I also have msmpeng.exe eating up 100% of my CPU. However, I do not find Windows Defender in my Programs menu, nor can I figure out how to access it through MSE. Would you please tell me how to turn it off through MSE? Thank you.

  11. I’m running Windows 7 with Microsoft Security Essentials and I also have msmpeng.exe eating up 100% of my CPU. However, I do not find Windows Defender in my Programs menu, nor can I figure out how to access it through MSE. Would you please tell me how to turn it off through MSE? Thank you.

  12. I found this service in XP under Microsoft Antimalware Service.

  13. I had my cable come out and charge me to set up lightning speed download up…to 40 mbps.

    Something is slowing this down and it is not like greased lightning. I have the task manager open right now and it is showing that iexplore is listed 2 times and mem usage is 96,164K and 10,676K. How do you know what programs are running and slowing down the computer? I don't want to delete something important

  14. Thankyou kei i found it under antimalware services.For people as green as me.Press start button >run> type in the box msconfig takes you to system configuration window open tab services uncheck antimalware services.It has done the trick for me

  15. This information, unfortunately, isn't true in my case. I have neither Windows Live One Care, nor do I have Defender running. In my case it's because I'm using Microsoft Security Essentials, and because of this, my CPU is running right now, @ about 55%. I'd really like to decrease this by at least half, but when I open MSE, there appears to be no way to do this…….Ahhhh Microsoft,….continuing to suck the life's blood out of us, one little app @ a time……

  16. open MSE, under Settings tab there are two areas where you may do this: Excluded files & locations (click Add, then c:program filesMicrosoft Security Essentials) and Excluded Processes (click Add, then c:program filesMicrosoft Security EssentialsMsMpEng.exe).

    Be sure to click Save Changes! Hope it works for ya.


    Todd in Vallejo

  17. I'm using Windows 7 with MSE – I followed todd94590's suggestions and that worked perfectly.

  18. Thank you so much, my PC is now working properly again ! Weird it began only a few days ago, while I am using Defender/Essentials for months but still !

  19. worked for me, was at 49% now i am at 2-4 percent. easy enough directions to follow.. thanks

  20. Uninstall the crap software from Microsoft and that should fix your problem.

  21. I am having a lot of trouble and found where I was supposed to check to see what was using the most and it is MsMpEng.exe system. I have read all of this but am not clear on what it is I'm supposed to do. please help me with step by step explanations. I only pretend to know what I'm doing! hehe

    Thank you for your help

  22. I am again having this same problem. MSMPENG exc eating all of my processor time. I can't find Windows Defender on my computer. I had it at one time but it is gone. I use MS Security Essentials. Could it be in that program? If not how can I get it out of my system.

  23. Other research shows that this is also in MS SE. Yesterday My SE would not up date. It got to 85% and said no connection. I had to remove and re-install it. Now my processor takes forever to load other programs and hard drive runs around for ever. Eventually it will cause my hard drive to wear out. Magic Jack will no longer load as it battles MS MPENG.

    I have to unplug Magic until MS MPENG gets through and then plug in Magic Jack. When will the security people not try to gram all of the processor on boot up? There's several that I will no longer use. Web Root is one. It seems sometimes it would be better to let the viruses come on in than to continually baby the security programs pop ups, processor seizing, etc.

    Does anyone know how to set the processer speed for MSENG from Normal to Below Normal or Low. Task Manager will not allow you to do this. I can turn it off but then I get the annoying popups immediately sayin I am not protected. I don't need this kind of protection. Does anyone know a good security program that does not grab all of the processor at start up? When you have two programs that do this then neither can load.

  24. If you use Windows XP, just remove this folder: C:Program FilesMicrosoft Security Essentials

    …I wanna Google Chrome OS!!! Sergey, Please!

  25. I don't have a desktop icon for Windows Defender – how/where can I find it to set the restrictions????

  26. I have the MsMpEng running on my computer, but I don't have Windows Defender or Windows Live One Care. My laptop originally came with Vista, but I changed it to Windows XP. How do I get rid of it now?

  27. I have Windows XP. Windows Defender is shut off but MsMpEng is still running near 100%. What do I next.

  28. I have MSMPENG and tuned the settings with the directions from here… Works like a bloody charm!! Cheers mates!!

  29. This is brilliant. I followed todd94590's directions for MSE. It took a few minutes to kick in, but I am definitely seeing a significant drop from my previous 100% usage, which was constant (right now it goes anywhere from 10% – 65%).

    My question is: How significantly does this affect the security of my laptop? Do infections commonly take place in in the MSE folder / process?

  30. todd94590, that was the answer, thanks. Shame some people can't be bothered to read what you typed eh?!

  31. If you disable MsMpEng entirely, Microsoft Security Essentials will NO LONGER FUNCTION. That means NO ANTIVIRUS PROTECTION from this program.

    Additionally, those of you who have a different antivirus installed… you should not be here. You should only have 1 antivirus installed and running at a time. Aside from being a waste of system resources to have more than one, most antivirus programs conflict with each other… thus making them ineffective anyway.

    Unfortunately, I do not have advice to reduce the system resources MsMpEng is taking up. I do, however, suggest you all go out and buy another stick of RAM to upgrade your computer as this helped me. If you don't know what I'm talking about, go ask someone who does. Or better yet, just Google it.

  32. I just uninstalled windows defender a couple days ago and I still get that crap process causing problems

  33. AweSum!

    Applied your first option of excluding the directory for scanning, saw in taskmanager that the program was still running at 25,000k.

    (I overlooked to check CPU usage)

    When I still saw 24000k, decided to omplement your 2nd option of turning off Defender.

    Had task manager opened to performance tabm and IMMEDIATLY the CPU usage dropped to 1-2%.

    I alredy have 2 spyware programs running, so will activate Defender periodically to update program and perform a scan, then de-activate again.

    Thank You! (and google)

  34. Windows Defender uses high CPU when it quick-scans at the appointed time each day. This can last a few minutes, depending upon the amount of data it has to scan.

    Try going to ToolsOptions, 'Automatically scan my computer' and set the time for when you're on lunch break, or some other time that won't bother you (if it does). Or you could just uncheck the option and manually scan every once in a while if you want.

    The rest of the time it uses minimal processer time – usually zero. For those who don't have it, the program 'Process Explorer' from Sysinternals will tell you exactly what's running, how much processer time each process uses as well as much more useful information and offers an option to kill the process.

  35. I have disabled Windows Defender completely and it still shows up on the processes. Is it supposed to be there or should it not?

  36. Hi I had the same problem working off XP.

    I have uninstalled Microsoft Security Essentials and Windows Defender. However the program kept running, even though I kept terminating it.

    The program is not found under "msconfig" or "services.msc". The problem, which I later figured out was that the uninstallation was not completed as the program was running during uninstallation and a general setting of antivirus software, is to just prevent this.

    My computer was, therefore, confused as to whether it was installed or not and the program keeps running.

    I, therefore, removed the program manually. To do this search for "Msmpeng.exe" on your local hard drive. I found mine at C:Program filesMicrosoft Security Essentials. I deleted the whole Microsoft Security Essentials folder (and left it in recycle bin, just in case I needed it). Though, I have other antivirus and antispyware software running so I do not think I would need it.

    I, then, terminated the program using Task Manager and it never came back. You will notice "MpCmdRun.exe" also will be removed (though it does not use as much of your memory).

    My computer is now running faster than ever with those services.


  37. I am running Windows XP and have the problem with MsMpEng.exe as well. I've tried MSCONFIG and turning Microsoft Security Escentials off. Prior to this, I had added the "exclude directory" fix first, but this didn't help.

    I cannot find Windows Defender in the whole of the computer and I am baffled why MsMpEng.exe is still running and STILL soaking up all of my computer's resources.

    Any ideas? Thanks!

  38. This little jewel is also inside of MS Security Essentials. The way to disable it is basically the same as with Defender.

  39. I found it, msmpeng.exe, was a heavy resource user with Norton Internet Suite under the files I was allowing to run screen.

    What was odd, was when I went to disable the scan of that file I got a box saying Windows Defender was turned off. Somehow, even though it was off, it was still a resource hog so I removed the program completely.

  40. I just found out that msmpeng.exe is also used by MS Security Essentials as its real-time protection tool. In that capacity, it's no longer titled as "Windows Defender", but as "Microsoft Antimalware Service" in the list displayed by services.msc or msconfig.

    As a matter of fact, XP users who haven't specifically downloaded Windows Defender will never even see "Windows Defender" as an installed program. Yet, they may still see "msmpeng.exe" listed as a running process in the Task Manager. Why? Because they have MS Security Essentials installed with its real-time protection enabled, and it's titling msmpeng.exe under its alias name, in services.msc or msconfig.

  41. Anyone contemplating taking either of these measures should understand the consequences of doing so …

    1. Turning off the service will leave your computer without protection.

    2. Excluding directories or files from the scan will provide a place for malware to be placed safe from detection.

    It would be better to set the scan to run at a time when you aren't using your computer or manually to start the scan when you're going to take a break.

  42. I can't find Windows Defender on my computer anywhere. I followed the instructions above and it's not there. I have the MsMpEng.exe eating up all my cpu. I am operating Windows XP.

    Help, please. Thanks.

  43. Thanks to todd94590. I didn't have defender or live care but have MSE. The fix worked. I wouldn't completely remove MSE. I actually intentionally installed it because lately MS has been doing a good job with it. It's perfect for WinXP and Vista, unlike defender which is the lamest excuse for malware protection I've ever seen. I use malawarebytes with what ever AV I put on a PC.

  44. Thank you all. MsMpEng.exe has baffled me for a while. Finding out it was part of Microsoft Security Essentials was a big help. I deleted MSE today. Computer speed increased greatly the minute I deleted it.

    MSE was more frustration than I need. I do have Norton.

  45. I'd finally thought I'd disabled this program forever, but it was just running without the icon or hard drive virus scans.

    Years later, I upgrade my PC and it crashes every 30 minutes. Thank you for finding the cause.

  46. Finally it is quiet. I was going to have to smash this computer if the hard drive didn't shut up. It was driving me out of my mind accessing the thing constantly and slowing the computer down. I just could not understand why a 2.8ghz i7 with 8GB of RAM was so, so slow.

    Peace at last!!!

    Thank You!!

  47. I have two computers. One at home, one at work. The one at home had Windows Defender and MSmpeng.exe and my system often ran at 99% causing extremely slow operation and often locking up altogether. My work computer, which also uses Windows XP, doesn't have Defender or MSMPeng. So I decided to rid my home computer of those two "evils." I uninstalled Windows Defender and deleted MSMPeng.exe and my home computer came back to life! No lockups, and it's as fast as superman again. So far, no problems from getting rid of those two items.

  48. My problem was solved by doing the following:

    First, I uninstalled Windows Defender. Then, I opened the process tab in the Task Manager, highlighted MSmpEng.exe, right-clicked it, then clicked on the END PROCESS TREE line.

    The MSmpeng.exe was totally gone and my computer is lightning fast again and doesn't lock up anymore!

  49. Hi, there.

    I have tried to follow your instructions but I don't have Defender on my PC. I do have this mmsmpeng thing running and it's driving me nuts.

    Any ideas?

  50. Simply disable the Microsoft Antimalware Service and you will all be free!

    DO NOT TRUST Microsoft when the subject is protect your PC. Better use the weak and very limited ClamWin than use anything from Microsoft because there is no a single piece of Microsoft code free of holes and bugs, and hackers love it.

    Windows 7 is fine as far as you protect yourself NOT TRUSTING Windows or Microsoft. Simple as that!

  51. @les – don't know if you're still "out there" as it's a year later … but thanks for your solution for those of us who aren't so tech-savvy! It worked.

  52. I just added Defender’s directory from scanning and it works great. From average of 65% CPU utilization down to occassional 6% utilization.

    Thank you

  53. I have windows xp and also do not have Defender on my PC.

    MsmPeng.exe is running and my computer is super super slow. Any help would be much appreciated. How do I turn it off without Defender?

    Please help!


  54. if you are using MS Security Essentials, the service for MsMpEng.exe is named "Microsoft Anti Malware Service" disabling it should kill the process..

  55. Hey guys,

    In my opinion, Windows Defender is cr*p. Uninstall it, ALL OF IT, and install Windows Live Essentials. That will download Windows Live Messenger, some other stuff, and Microsoft Security Essentials. MSE is much better than Windows Defender, and it doesn't use up as much CPU than Windows Defender.

    If you guys are still having problems, include an @TechyDude in your comment. Thank me if my info helped!

  56. @Idell I think what you need to do is just do what Barry said. Open up Windows Task Manager, go to the Processes tab, highlight msmpeng.exe, and click the "End Process" button. Thank me if it helped.


  57. MsMpEng is also used by Security Essentials. If you have Defender -or- Security Essentials, you will have msmpeng.exe

    Having both installed is a documented bad idea. They both use the same monitoring hooks and end up fouling each other up. In general, having two types of ANY real-time security monitoring software installed is a bad idea, due to the potential for recursive intercept.

    Incidentally, ANY effective real-time security software will eat a lot of cpu, memory-IO and disk-IO, and will seriously slow your computer down. The microsoft tools aren't particularly EFFICIENT, but they're not that much worse than any of the EFFECTIVE competition.

    "Security theatre" software usually doesn't slow down your computer much, but it usually doesn't PROTECT it much, either.

  58. Thank you so much! It was running my computer right down and now it is running at a much better pace :). Also discovered I had other processes running that were eating a lot of my memory, grrrr!

  59. Same thing – no Defender running, but I do have MS Security Essentials. I opened it and changed the settings. No more monitoring file & program activity, excluded itself, and the external drives. Will see if that helps.

  60. Windows XP Proffesional service pack 3, Microsoft Security Essentials 2

    Excluding maps and processes from MSE were no good (and I bet, not that good considering possible infection of MSE itself)

    My problem was residual left overs from an old anti-virus program (Norman Virus Control v5.99).

    There was no trace to be found of the old program, no file, no registery info.

    Only hint was the security centre of windows which told me I had more then one anti-virus installed.

    Problem was, it didn't tell me which it was, just saying 'more then one, and at least 1 was updated and functioning'.

    Had to uninstall MSE to learn from the security centre what other program was 'installed', which was Norman.

    Had to reinstall Norman and 'correctly uninstall it via the official uninstall file, restart, reinstall MSE and it was done. :-D

  61. Yea, My computer wont let me turn windows defender on in the first place, it says it off. However i constantly receive reports from Norton that msmpeng.exe is using a lot of my processing power. When i go look at my processes in the task manager im ususally at 96-100%. Anything i can do?

  62. For Windows XP SP3 with Microsoft Security Essentials do this (thanks to todd94590)
    1. Open MSE, go to Settings
    2. Add "c:program filesMicrosoft Security Client" and "c:program filesMicrosoft Security ClientAntimalware" to Excluded files and locations
    3. Add "c:program filesMicrosoft Security ClientAntimalwareMsMpEng.exe" to excluded processes

    Be sure to click Save Changes! Hope it works for ya.

  63. Followed instructions from Todd in Vallejo. Thank you Todd!

  64. Thanks..On disabling Microsoft Antimalware Services from msconfig’s services did the trick.. Thanks again..

  65. Timeless advice, still helping people (me) years after being published! I did, of course, benefit from many of the replies as well (thanks everyone!) and I do hope you will edit the article to incorporate some of the additional advice into the main article since not everyone reads the comments (apparently.)

    In my case I have MsSE yet this subprogram “msmpeng.exe” was running at a time I had not scheduled a scan. As it turns out, the uninstall of Windows Defender must have been incomplete, and this was the result. I have had scheduled scans take in excess of 12 hours and this is not acceptable to me. I think it might take less time to reinstall the operating system each day and just keep all my data files in the cloud similar to what chrome book does and thus make anti-malware programs unnecessary for my computer, freeing up 100% of my processor for use by me.

  66. Good tip. Thanks, Checker04. I also noticed that this dubious MsMpEng.exe can still once in a while go into a CPU feeding frenzy – probably a circular referrence similar to the dog-chasing-its-tail scenario that your tip prevents here. When that happens, I terminate its process tree via the task manager, then trigger its auto-reload by just accessing the Microsoft Security Essentials app that shows a red flag as soon as MsMpEng.exe shuts down (… I hear you: “Throw this MS Security Essentials app out!”… I actually am wearing belt and suspenders at once on this one, since I have another malware protector that has been peacefully co-existing with MS Essentials…)

  67. Thanks dude, I was so pissed off with this problem. But the difference is I am using Microsoft Security Essentials, but the same remedy given by you helped me in reducing my CPU usage.

  68. Followed instructions from Todd in Vallejo. Life is much better now. Thanks!!!

  69. windows defender has been turned off for months, but this is certainly an issue.

    Now what?

  70. Thank you a thousand times; after exluding the Windows Defender folder an enjoyable silence came over my PC. Disk usage went down to almost zero kB per second. I can’t believe Microsoft does not fix this themselves.

  71. I have this process eating CPU, and I have Windows Defender turned off.

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