What Is Msmpeng.exe?

by Nick Davis

Msmpeng.exe is the scanning component of the PC program Windows Defender. Windows Defender is a free program that protects your computer from security threats, spyware and viruses. Msmpeng.exe is not a virus or other type of malicious file. It performs a scan of your system according to the schedule set within Windows Defender. You can view what Msmpeng.exe is scanning via Windows Defender’s interface.

Windows Defender

Windows Defender is available directly from Microsoft and is compatible with Windows 7 and older versions of the operating system. The program includes an installation wizard that guides you through setting up the program on your computer and scheduling when it should scan for problems. The program doesn't require a product code or any special add-ons to complete the installation process.


Windows Defender’s msmpeng.exe launches and scans your computer for spyware as well as worms and Trojans – two other malicious file types that invade and possibly destroy your computer. Msmpeng.exe removes and quarantines infections it finds. The program also shields your computer from future spyware infections.

Task Manager

Msmpeng.exe, like other programs and processes, appears in your computer’s Task Manager under the “Processes” tab and you can stop the program via this utility, if desired. Stopping msmpeng.exe from running stops the scanning process and may result in viruses, worms and other infections being left on your computer.


Msmpeng.exe loads automatically when you download and install Windows Defender on to your computer. The program is also present in Windows Live OneCare, a performance and security suite by Microsoft that is no longer available. Msmpeng.exe within Windows Live OneCare performs the same function as in Windows Defender – scanning for spyware. If you uninstall Windows Defender or Windows Live OneCare, msmpeng.exe is also uninstalled. The program cannot run on its own without one of the two programs installed.

About the Author

Nick Davis is a freelance writer specializing in technical, travel and entertainment articles. He holds a bachelor's degree in journalism from the University of Memphis and an associate degree in computer information systems from the State Technical Institute at Memphis. His work has appeared in "Elite Memphis" and "The Daily Helmsman" in Memphis, Tenn. He is currently living in Albuquerque, N.M.