The Microsoft Malware Removal Tool – How Well Does It Work?

Chris Hoffman 09-03-2012

microsoft malware removal toolIf you keep an eye on the updates Windows installs, you may notice the Microsoft Malicious Software Removal Tool appearing every month. It removes some malware programs, but only a few — it doesn’t replace the need for an antivirus.


Microsoft’s malware removal tool exists as a sort of band-aid for the lack of antivirus in Windows. It attacks and removes prevalent malware, particularly worms, slowing their spread and preventing them from doing much more damage. It’s no substitute for an antivirus, which guards your system from a larger amount of threats, preventing them from taking root in the first place.

How the Microsoft Malware Removal Tool Works

On the second Tuesday of every month — Microsoft’s “patch Tuesday” — Microsoft releases a new version of the Microsoft malware removal tool. Windows Update downloads the updated tool, if you have it set to automatically install updates, and runs it in quick-scan mode. The tool quickly checks to see if a handful of common malware programs are running, and removes them if they are.

microsoft malware removal tool

Its Purpose

This tool was created by Microsoft to help counteract fast-spreading malware A Brief History Of The 5 Worst Computer Viruses Of All Time The word "virus" and its association with computers was affixed by American computer scientist Frederick Cohen who used it to describe "a program that can 'infect' other programs by modifying them to include a possibly... Read More , such as the Blaster, Sasser and Mydoom worms, which infect a large amount of computers. Malware programs like these don’t only affect a single computer — each newly infected machine produces more traffic and infects other machines.

malware removal tool


With the Microsoft malware removal tool, Microsoft can quickly remove prevalent strains of malware from a large number of computers at once, slowing the spread of particularly virulent malware. It mitigates the damage done by users who don’t run an up-to-date antivirus, but it doesn’t replace the need for an antivirus.


The tool has extremely significant limitations. It:

  • Detects only malware that’s already infected your computer.
  • Removes only a few strains of malware.
  • Detects only malware running on your system.
  • Updates and scans your system only once per month.

Why You Still Need An Antivirus

Antivirus programs are the mirror image of the Microsoft Malware Removal Tool. They:

  • Prevent malware from running in the first place.
  • Try to detect every known malware program.
  • Scan your entire system for malware that may be hiding on your file system, but not actively running.
  • Run all the time, updating once per day — or more.

Running It Manually

While Microsoft’s malware removal tool usually runs in quiet mode, with no user intervention, you can also run it manually. Type “mrt” into the search box in the Start menu press Enter to run the mrt.exe file.


malware removal tool

If the tool is more than 60 days old, it will prompt you to download a newer version. As you can see, Microsoft recommends running an antivirus product instead.

malware removal tool

Click the “View a list of malicious software that this tool detects and removes” link and you’ll see a short list of malware. You can also view this list on Microsoft’s website.


free malware removal

From this window, you can do a full scan of the files on your computer instead of just doing the standard “quick scan.” To be honest, there’s not much value in running the full scan. If you’re going to do a full, in-depth scan, you should do it with a complete antivirus program. The full scan still only detects a few types of malware.

free malware removal

If you do a scan, you’ll hopefully see a message saying “No malicious software was detected.” As the tool only checks for a few types of malicious software, you can’t be sure that no malicious software is present on your system.


free malware removal

Using An Antivirus Program

Microsoft provides their own free antivirus program, Microsoft Security Essentials Free Security Suite for Windows: Microsoft Security Essentials Read More , which you can download from Microsoft’s website. You can also use another free antivirus program The 10 Best Free Antivirus Software No matter what computer you're using, you need antivirus protection. Here are the best free antivirus tools you can use. Read More  instead. The Microsoft Malware Removal Tool isn’t good enough to rely on.

microsoft malware removal tool

Windows 8 Will Windows 8 Succeed Or Fail? [Opinion] Microsoft is trying to make Windows 8 be all things to all people. Or at least all operating systems to all devices. A risky strategy that has rarely, if ever, worked. This is Microsoft reaching... Read More will have a built-in antivirus program, eliminating the need for Microsoft’s malware removal tool.

Do you use Microsoft Security Essentials, or do you prefer another antivirus product? Leave a comment and let us know.

Image Credit: Laptop with Bacteria via Shutterstock, Computer Worm Illustration via Shutterstock

Related topics: Anti-Malware, Computer Maintenance, Trojan Horse, Windows 7.

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  1. Mark
    March 18, 2016 at 9:38 am

    Hi, if the MRT only runs once a month, can you tell me why it requires internet access frequently every day? Thanks.

  2. Faisal Ahmed
    August 25, 2012 at 6:44 am

    So, do you suggest using another anti-virus software other than MSE; if so, which one?

    • Chris Hoffman
      August 27, 2012 at 9:13 pm

      I use MSE myself. But the Microsoft Malware Removal Tool installed by Windows Update is different -- it's not a proper antivirus.

  3. Ben
    June 20, 2012 at 9:59 am

    I use Microsoft Security Essentials. Windows Defender is disabled on my system. I wonder if this is adequate or should I be running both?

    • Chris Hoffman
      June 20, 2012 at 10:42 pm

      That's normal! MSE disables Windows Defender when you install it. MSE basically includes Windows Defender's features.

      Running multiple antivirus-type programs can cause problems, so you're all good.

  4. Siddharth
    March 28, 2012 at 6:23 am

    I think we cant rely on MSE as this antivirus is very basic.A person need to buy a good antivirus

  5. Siddharth
    March 28, 2012 at 6:23 am

    I think we cant rely on MSE as this antivirus is very basic.A person need to buy a good antivirus

    • Chris Hoffman
      March 28, 2012 at 8:16 am

      Being "basic" isn't necessarily a bad thing. The major antivirus vendors pack features and options in, but the core antivirus functionality is the important part.

      The real test of MSE is how it stacks up against other antiviruses in detection tests. Comparing "features" doesn't mean much.

      Personally, I love how basic MSE is. I don't need the pile of features that are crammed into commercial antivirus programs to justify their price tags.

  6. antivirus
    March 12, 2012 at 3:48 am

    This is a smart blog. I mean it. You have so much knowledge about this information, and so much passion. You also know how to make people rally behind it, obviously from the responses. You've got a design here that not too flashy, but makes a statement as big as what you're saying. Great job, indeed.

  7. dado023
    March 11, 2012 at 2:56 am

    Avast is the best choice for me; tried avira, microsoft, avg, norman and few more.
    Avast was the only one able to detect bad web pages with malicious java i even uninstalled kaspersky, because it couldn't detect bad web pages.

    • Chris Hoffman
      March 11, 2012 at 5:14 am

      Interesting. Of course, if your web browser is up-to-date, malicious javascript shouldn't be a problem.

      Still, there's a lot to be said for an antivirus that can notice these sorts of things -- good point.

  8. Bob Keller
    March 10, 2012 at 6:15 pm

    I use Kaspersky on all 3 of our computers.

    • Chris Hoffman
      March 10, 2012 at 8:32 pm

      Hi Bob, any reason you prefer Kaspersky?

    • paul w
      June 21, 2017 at 4:15 pm

      Bob - I would suggest you remove Kaspersky from every device and rebuild your OS from scratch. Russians have been stealing your data for 5 years now.

  9. Yang Yang Li
    March 10, 2012 at 3:45 am

    I just have to comment on this article to show my love for Avast!
    Compared with AVG, avast! blows it out of the water. Even the free version is insanely effective. But for all of you who are fans of other antivirus programs, remember avast! offer the best free protection out there.

    • Chris Hoffman
      March 10, 2012 at 1:44 pm

      Avast! has been pretty good to me, too. Why do you prefer it to AVG?

  10. brentrjones
    March 10, 2012 at 1:58 am

    I have been using MSSE for as long as it has been out.  As a part-time PC technician I have installed it on many computers.  It works fine and stays the heck out of the way.  Price is exactly right.

    • Matt
      March 10, 2012 at 2:57 am

      I've had a lot of call-outs to fix computers that have had MSSE and ended up still getting compromised by viruses or malware. At one point, MSSE is about the worst in terms of detection rates. Most of the other free AV oroducts are better, especially Avira, AVG and Avast.

      • Jamie McCutchen
        March 10, 2012 at 3:37 am

        That's a load of crap! NONE of those free versions are any better, in fact I would say they are all lesser overall, than MSSE. You had best check your facts because you are WAY off base.

      • Damian A
        March 10, 2012 at 7:23 am

        Actually Avira (scanned from HBCD USB) detected a Trojan that security essentials never found on my dad's computer.It could be a good idea to have more than one security program, one installed on your computer and one live CD or USB version that updates when you run it and then scans, something you can do when you'll be away (it took all night but that computer has an IDE hard drive and USB 1.1) for a while.

        I do like MSSE, though. In that it's light and "stays the heck out of the way" like brentrjones says. Avast is another I like but people might find the alerts annoying and, at least last time I checked, you have to look through the options some to find how to disable them completely. 

        • Chris Hoffman
          March 10, 2012 at 1:48 pm

          If you think there's a problem, running a scan with multiple programs is definitely a good idea.

          It's also possible that the trojan was hiding itself from MSE. It may have only been possible to see if from outside the operating system (with the boot CD, it wasn't running in memory and playing games).

      • Chris Hoffman
        March 10, 2012 at 1:46 pm

        I'd definitely be interested in seeing an actual study comparing detection rates. They tend to go out-of-date fast.

        Every AV product will miss something.

  11. Aaron Couch
    March 9, 2012 at 9:41 pm

    I have used Avira Antivirus, Avast and AVG, but now I am using MSE and really like it! I recommend it to everyone too, specifically because it has an easy to use user interface.

    • Chris Hoffman
      March 9, 2012 at 11:45 pm

      I love MSE's interface. Unlike other free antivirus programs, it doesn't try to "upsell" me to a paid product

  12. Howard Pearce
    March 9, 2012 at 9:19 pm

    Norton has had pretty good ratings in recent years and I can get it free with my Comcast as my ISP ... so I use that. It has both av and firewall components.

    • florin
      March 9, 2012 at 10:47 pm

      @bb8ddda02d3a2083de79a065e6b2b43f:disqus If you're not advertising for Norton, then please stop recommending it. I don't want to say it sucks, but it sucks. Norton did a good job over 10 years ago, but their products went down hill starting with Norton Antivirus 2000 (yes, 10 years ago). If I were to recommend a security company, it would b e ESET and if I were to recommend an antivirus, it would be ESET NOD32. If you want free, go with AVG, but if you really care about your computer and personal information (name, address, online accounts, bank accounts, passwords) then you should fork your money to ESET or Kaspersky and forget about "free" antivirus.

      • Chris Hoffman
        March 9, 2012 at 11:47 pm

        I've used NOD32 in the past. It's a great product (at least, it was then.)

        I completely disagree about free antiviruses, though -- free antiviruses should work fine.

    • Chris Hoffman
      March 9, 2012 at 11:46 pm

      I wouldn't recommend Norton. I've heard it's gotten a bit better, but it used to be extremely bloated and slow.

    • Matt
      March 10, 2012 at 2:54 am

      Norton is very thorough, but it's also very very slow compared to a lot of products, and quite a few other programs seem to conflict with it. If you switch to Eset, you'll never go back to Norton.

      • Ankur
        March 10, 2012 at 3:23 am

        Pls update urself. Its not bloated now.
        I personally also like eset.

        • Chris Hoffman
          March 10, 2012 at 1:45 pm

          It may be better, but there are a lot of people (like me) who remember it as bloated. When we're already happy with our existing antivirus -- particularly free ones! -- why would we go back and try Norton?

        • Ankur
          March 11, 2012 at 3:24 am

          I agree. I fully support Free AV. 
          But I am telling not to say wrong about something you don't have full details of.

          I never told anyone to try Norton. But I just wanted to tell that it is now one of the most fastest AV. Pls read independent  online guides like Av-test and Av-comparatives. 

          Again, Please dont think I am from Norton or something. :)
          I test a lot of AV fro my site, thats how I know this.

        • Chris Hoffman
          March 11, 2012 at 5:13 am

          Thanks for sharing, Ankur. You make a good point -- our perceptions may be out of date. I'm happy to hear that Norton has improved (it had a lot of room for improvement!)

    • LEH
      April 16, 2015 at 2:50 pm

      Norton admits that hackers got hold of their source code in 2006:

      I saw lots of computers compromised by the FBI Fakeware that were running NAV. In addition, I frequently had to remove customers NAV in SMWN because it was blocking all Internet traffic in normal mode.

      Microsoft Security Essentials? You may as well be running nothing. It has failed industry standard bench testing for some time now. I hear people say that they run it and have no problems. Yup. Until you run a different AV or malware software and show them all of the adware/spyware and malware the got through and is the reason the system is so very slow.

      But people will continue to defend it because it is free, it is from Microsoft and they argue that who better to patch Windows than Microsoft? Sounds logical except that the number of problems with Windows code has risen with each release. I would not trust an AV written by the company whose code made AV necessary in the first place.