The best way to tell if you have anti-virus software installed is to use the Security Center feature on your Microsoft operating system. When you select this option, you’ll be presented with a status of antivirus software (installed, enabled, and still up-to-date, and etc.)

If your computer is running Windows 10

You can do this by following these simple steps:

Clicking Start > Settings > Update & Security > Windows Defender

If you installed an antivirus program, Windows Defender is disabled.

If Windows Defender is turned off and you don’t have any antivirus program installed (or the antivirus program you installed doesn't work), you will see a warning in the notification area on your taskbar.

Windows doesn’t detect all antivirus software, and some antivirus software doesn’t report its status to Windows. If your antivirus software isn’t displayed in the Action Center and you’re not sure how to find it, try any of the following:

• Type the name of the software or the publisher in the Search box on the Start menu.
• Look for your antivirus program’s icon in the notification area of the taskbar.

If your computer is running Windows 8

• Users using the classic start menu:  Start > Settings > Control Panel > Security Center.
• Users using start menu: Start > Control Panel > Security Center.

If Windows Defender is turned off and you don’t have another antivirus program installed (or your other antivirus program is not working), you will see a warning in the notification area on your taskbar.

Windows doesn’t detect all antivirus software, and some antivirus software doesn’t report its status to Windows. If your antivirus software isn’t displayed in Action Center and you’re not sure how to find it, try any of the following:

• Type the name of the software or the publisher in the Search box on the Start menu.
• Look for your antivirus program’s icon in the notification area of the taskbar.

If your computer is running Windows 7

Windows 7 includes spyware protection, but no antivirus protection.

To find out if you already have antivirus software:

1. Open Action Center by clicking the Start button , clicking Control Panel, and then, under System and Security, clicking Review your computer’s status.
2. Click the arrow button  next to Security to expand the section.

If Windows can detect your antivirus software, it’s listed under Virus protection.

If your computer is running Windows Vista

By default , Windows Vista does not include virus protection. 

The status of your antivirus software is typically displayed in Windows Security Center.

1. Open Security Center by clicking the Start button , clicking Control Panel, clicking Security, and then clicking Security Center.
2. Click Malware protection.

If Windows can detect your antivirus software, it will be listed under Virus protection.

Windows does not detect all antivirus software, and some antivirus software doesn’t report its status to Windows. If your antivirus software is not displayed in Windows Security Center and you’re not sure how to find it, try any of the following:

• Look for the antivirus software in the list of programs on the Start menu.
• Type the name of the software or the publisher in the Search box on the Start menu.
• Look for the icon in the notification area of the taskbar.

If your computer is running Windows XP

Click the security icon on the taskbar, or click Start, select Control Panel, and then double-click Security Center.

On April 8, 2014, Microsoft ended support for Windows XP. This means that after April 8 2014, there would be no new security updates available through automatic updating for computers that are still running Windows XP.