Windows NT 3.5 is the second release of the Microsoft Windows NT operating system. It was released on 21 September 1994 in two versions: Workstation and Server.

The Workstation edition allowed only 10 concurrent clients to access the file server and no Mac clients. The Server edition included all of the functions and network options.

This is the first Windows NT to adopt the names Windows NT Workstation and Windows NT Server for its editions. The editions of the previous Windows NT release, Windows NT 3.1, were named Windows NT and Windows NT Advanced Server.