The Windows Installer CleanUp Utility is a legacy software utility for the Microsoft Windows operating system designed to solve installation problems of apps that use the Windows Installer technology.

An app whose Windows Installer entries are damaged cannot be uninstalled or reinstalled via the normal means.

The Windows Installer CleanUp utility removes all files and registry settings associated with an app's Windows Installer database, allowing it to be reinstalled.

Only users who have logged in as system administrators may run the utility.

[1] Microsoft first released the utility in 1999[2] to help Windows-based computers clean up installed programs that would either refuse or pretend not to remove themselves from the "add/remove programs" feature in Microsoft Windows.