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Microsoft Security Essentials is a free* download from Microsoft that is simple to install, easy to use, and always kept up-to-date so you can be assured your PC is protected by the latest technology.

Microsoft Security Essentials runs quietly and efficiently in the background so you’re free to use your Windows-based PC the way you want—without interruptions or long computer wait times.

Before installing Microsoft Security Essentials, we recommend that you uninstall other antivirus software already running on your PC. Running more than one antivirus program at the same time can potentially cause conflicts that affect PC performance.

Files

Status: Deleted This download is no longer available on microsoft.com. The downloads below are archives provided by the Internet Archive Wayback Machine from the Microsoft Download Center prior to April 2023.

Files
MSEInstall.exe SHA1: f255da05d374eb6bc3c33eb6d0f8cdc212131811 Size: 9.46 MB
MSEInstall.exe SHA1: 76d6a97a3850126556f037e4537633c09fdbf84a Size: 7.47 MB

File sizes and hashes are retrieved from the Wayback Machine’s indexes. They may not match the latest versions of files hosted on Microsoft servers.

Minimum system requirements for Microsoft Security Essentials

Operating System: Windows Vista (Service Pack 1, or Service Pack 2)*; Windows 7*

• For Windows Vista and Windows 7, a PC with a CPU clock speed of 1.0 GHz or higher, and 1 GB RAM or higher.
• VGA display of 800 × 600 or higher.
• 200 MB of available hard disk space.
• An Internet connection is required for installation and to download the latest virus and spyware definitions for Microsoft Security Essentials.
• Internet Browser

Click the Download button on this page to start the download, or choose a different language from the drop-down list and click Go.