How to Properly Scan Your Computer for Malware

Rid Your Computer of Trojans, Viruses, Spyware & More

Photo of a virus indication key on a red computer keyboard
© Steven Puetzer / The Image Bank / Getty Images

Completely and correctly scanning your computer viruses and other malware like Trojan horses, rootkits, spyware, adware, worms, etc. is often a very important troubleshooting step. A "simple" virus scan will no longer do.

Many forms of malware cause or masquerade as seemingly unrelated Windows and PC issues like Blue Screens of Death, issues with DLL files, and other serious Windows problems so it's important to properly check your computer for malware when working to solve many problems.

Note: See my Free Bootable Antivirus Programs list if you need to scan for viruses but don't have access to Windows right now. More serious viruses can prevent your operating system from starting in the first place and so you'll have to use one of those tools instead.

Time Required: Properly scanning your PC for viruses and other malware is easy and could take several minutes or longer. The more files you have, and the slower your computer is, the greater the time the scan will take.

How To Scan Your Computer for Viruses, Trojans, and Other Malware

Applies To: These are general steps to scan and remove malware from your PC and should apply equally to Windows 10, Windows 8 (including Windows 8.1), Windows 7, Windows Vista, and Windows XP.

  1. Download and run the Microsoft Windows Malicious Software Removal Tool. This free, Microsoft provided malware removal tool won't find everything, but it will check for "specific, prevalent malicious software" which is a good start.

    Note: You may already have the Malicious Software Removal Tool installed. If so, make sure you update it using Windows Update so it can scan for the latest malware.
  1. Update your anti-virus/anti-malware software installed on your computer.

    Before running a complete malware/virus scan, you need to make sure the virus definitions are up to date. These regular updates tell your antivirus software how to find and remove the latest viruses from your PC.

    Tip: Definition updates usually happen automatically but not always. Some malware will even specifically target this feature as part of its infection! Look for an Update button or menu item to start the check-and-update process for your antivirus program.

    Important: Don't have a virus scan program installed? Download one now! There are several free anti-virus programs available so there's no excuse for not running one. On that note - stick to one. It might seem like a good idea to run multiple antivirus programs at once but in reality that usually causes problems and should be avoided.
  1. Run a complete virus scan on your entire computer. If you happen to have another non-persistent (not always running) antimalware tool installed, run that too when this is done.

    Note: Don't simply run the default system scan which may not include many important parts of your PC. Check that you're scanning every part of every single hard drive and other connected storage device on your computer.

    Specifically, make sure any virus scan includes the master boot record, boot sector, and any applications currently running in memory. These are particularly sensitive areas of your computer that can harbor the most dangerous malware.

More Virus & Malware Scanning Help

If you've scanned your entire computer for viruses but suspect that it may still be infected, try a free on-demand virus scanner next. These tools are great next steps when you're pretty sure that your computer still has an infection but your installed antivirus program didn't catch it.

An online virus scan is yet a further step you can take, at least in situations where you have a good idea what file(s) may be infected. This is less likely to be the thing that fixes the problem but worth a shot as a last resort - it's free and easy to do.

More From Us