Windows 3.x0, released in 1990 and also known as Windows Version 3.x0, can refer to either an individual or all of the following versions of Microsoft Windows:
- Windows 3.00a (Windows 3.0 with Multimedia Extentions 1.00)
- Windows 3.10
- Windows 3.10 for Pen Computing 1.00 (Windows 3.10 for Pen Computing 1.0)
- Windows 3.10 for Workgroups (Windows for Workgroups 3.10)
- Windows NT 3.x0