Microsoft Belief Networks (MSBN) is a set of tools for Bayesian inference. The program is written in Visual Basic 4.0 and runs on Windows NT and Windows 95. It consists of an executable file and a set of Dynamic Link Library routines.

The main program supports the following:

- load and save Bayesian networks in the Bayesian network interchange format.
- create and modify networks by adding nodes and vertices.
- assess discrete probabilities.
- construct single-decision influence diagrams.

The program will be extended so that it is capable of learning networks from databases.