Windows Defender and Microsoft Security Essentials: Which one do I need?

UPDATE: For the most relevant information on Microsoft Security Essentials, please visit the Microsoft threat detection information page. We can ensure this page stays updated with the most relevant information on how to help protect your PC.


Depending on which operating system your computer is running, you can use either Windows Defender or Microsoft Security Essentials to get rid of malicious software and viruses.

If your computer is running Windows 8, you can use the built-in Windows Defender to help you get rid of viruses, spyware, or other malware. If your computer is running Windows 7, Windows Vista, or Windows XP, Windows Defender only removes spyware. To get rid of viruses and other malware, including spyware, on Windows 7, Windows Vista, and Windows XP, you can download Microsoft Security Essentials for free.

In Windows 8, Windows Defender replaces Microsoft Security Essentials

You can’t use Microsoft Security Essentials with Windows 8 or Windows RT, but you don’t need to because Windows Defender already provides built-in protection.

What is Windows Defender Offline?

Some malicious software will not allow you to access Windows Defender or other antivirus software. To help detect and remove the malware, you can start your computer by using a Windows Defender Offline CD, DVD, or USB flash drive.

Get step-by-step instructions for removing a virus.

About the Author
Eve Blakemore

Group Manager, Trustworthy Computing

Eve Blakemore is a Group Manager for Trustworthy Computing who delivers consumer guidance around the latest trends in security and privacy. Eve joined Microsoft in 1998 and has worked in corporate and field roles with Microsoft Learning, US Public Sector, Read more »

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  1. Anonymous

    My last 3 Windows Defender updates (I have Windows 7) have failed (see below).  I ran a trouble shooter but it could not ID my error code.  All Defender updates prior to Oct 26 were successful.  All other Windows updates through Nov 14 have been successful.  What is going on here?

    Definition Update for Windows Defender – KB915597 (Definition 1.161.1906.0)

    Installation date: ‎11/‎14/‎2013 10:24 PM

    Installation status: Failed

    Error details: Code 8007007E

    Definition Update for Windows Defender – KB915597 (Definition 1.161.1215.0)

    Installation date: ‎11/‎1/‎2013 9:09 AM

    Installation status: Failed

    Error details: Code 8007007E

    Definition Update for Windows Defender – KB915597 (Definition 1.161.695.0)

    Installation date: ‎10/‎26/‎2013 10:00 PM (Also Oct 27 & 28 attempts failed)

    Installation status: Failed

    Error details: Code 8007007E

  2. Anonymous

    please i need help, my Pc OS is window 7 home edition it came with an in-built window defender now Can i run and allow windows defender and Microsoft security essential on the same system

  3. Anonymous

    Yes,you can use both of them just download Microsoft security essentials from Microsoft website's download center…

  4. Anonymous

    Please can you clarify – if I have Windows 7 do I just need Microsoft Security Essentials or would I get more comprehensive protection if I also had Windows Defender?

  5. Anonymous

    My Virus Protection is "OFF"  please i need help to put it on again.  Thanks

  6. Anonymous is a radio station I love listening to for years, it is four weeks now it stopped abprutly, and I just cant get it to work.  What annoys me is, I am able to get all other radio stations in the same radio, on trying to connect, i am getting a message Windows Player cannot play the file because the specified protocol is not supported.  What should I do, please, please, Help me.  Thanks

  7. Anonymous

    torino72- try uninstalling the program and redownloading it. If that doesn't work go to command prompt -cmd- and type in sfc /scannow to scan for memory problems. Other solutions might include compatibility, anti virus block, lack of admin rights or missing an .dll.  You could also try running event viewer to.

    Godbest- Yes, but it is recommend you run 1 real time anti virus at the time because of resources taken. 1 anti virus + firewall is probably your best choice right now.

  8. Anonymous

    Yes you need to install Microsoft Security Essential for Windows 7 or XP. But you don't need to install it on Windows 8.

  9. Anonymous

    protect my system

  10. Anonymous

    I do not want Systweak Software because filing complaint against them .Any other that is in United States and recommended is OK

  11. Anonymous

    once I turned defender  on … to run a  once -off  scan … I now  cant  turn  it  off … showing  me  2  anti-virus   programs …  im  using  Norton 360 ….. can  someone   help ???     thanks ….    cheers    all ….

  12. Anonymous

    Someone is always changing my email password, how do i stop this?

  13. Anonymous

    Hello Godbest,

    You are confused!   Not surprising as Microsoft have a distinct lack of originality in naming their products!

    Defender in Windows 7 is anti-spyware (only).  Microsoft security essentials is the anti-virus and ant-spyware and when M.S.E is installed it disables defender.

  14. Anonymous

    How do I view a CD that is already loaded. It has MRI slides. I only wish to view

  15. Anonymous

    IAN – many thanks…. your reply to 'godblest' also very much helped me…

  16. Anonymous

    Very useful Forum. I am fervently appealing to jonnyzero to rteveal to me that processs of turnig  Defender on

  17. Anonymous

    very new to the computer world.  It is an old, re-built comp. that I am using as the acer one was borrowed and not yet returned.   So is this a "blog"  i am on?  how do i check for my answers?   how do you get into blogs?  or how and where on the computer can i start one?   also, I have no spell check.  do you know where i can get it.  everyone i know seems to have spell check, grammar check, thusorous (i know that is really not the correct way to  spell it but i think you will know what i  mean.  I did try downloading a spell check but nothing is working for me.  I think, for me, i should use blogs to learn about the computer world as there is  so much out there with facebaook, etc.  but i don't know where to go or what to do.  also the spell check is a major need for me.     thank you so  much.   now i will have to figure out where to pic up my answers, or do they go  right into my mail which is yahoo right now.

  18. Anonymous

    How do I turn Windows defender on? I have Windows 8.

  19. Anonymous

    I had viriuses on computer. got trend micro to delete from my computer run fine.On few sites, on line dating and Google.Do I delete on line helpfrom trend micro, my tecnician or unistall or both how uninstall.Not pay monthly fee

  20. Anonymous

    You are not paying for Anti-Virus and you are going to dating sites, you deserve to have viruses, Have any of you thought of using  Bing or Google to ask your questions

  21. Anonymous


    I am running W8 with built-in defender/security protection… But I see that I can not run the Istation program (… I tried another W8 computer with Macfee protection and I do not see any issues… Please suggest…


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