MSBNx: Bayesian Belief Network Editor and Toolkit

Everyday life presents us with many situations in which the accumulation of evidence leads to a conclusion.
[Menu Bar]
[A sample Bayesian Network]

Click Here to Download MSBNx

You may use MSBNx non-commercially. See the End-User Agreement for details.

For background information, see the MSBNx technical report.

Check the FAQs for help with download and running problems.

If you'd like to receive announcements about MSBNx, send an empty email to

What's New

6/16/2010 - The MSBNx sample code is now available for C# 4 and VS2010:

9/20/2007 - The MSBNx sample code is now available in C#:

1/31/2007 -- The first time you run MSBNx under Windows Vista, you'll get this pop-up message: "DLL Self-registration failed for HMMAddinLib.dll". Click "OK" and ignore the message.

9/10/2001 -- If you get a Run-Time 13 error when you try to run MSBNx, check the FAQs for a fix. The FAQs also include help for timeout during downloads.

08/02/2001 -- Before installing a new version, you must uninstall the previous version.

08/02/2001 - Reading models from the WinMine tool not supported for now. We are working on the issue.

08/01/2001 - Released version - changes the default Value of Information measure for diagnosis to entropic. This avoids a problem with the KL-distance based measure.


MSBNx is a component-based Windows application for creating, assessing, and evaluating Bayesian Networks, created at Microsoft Research.� The application's installation module includes complete help files and sample networks.� Bayesian Networks are�encoded in an XML file format. The application and its components run on Windows 98, Windows 2000, and Windows XP.

Comments and Questions

Please email with your comments or questions.


See the Background page for information on how Bayesian Networks are useful for diagnose and troubleshooting.


[Example of recommendations]When doing diagnosis and troubleshooting, MSBNx can recommend what evidence to gather next.

If you give MSBNx cost information, it does a cost-benefit analysis. If no cost information is available, MSBNx makes recommendations based on the Value of Information (VOI).


MSBNx tries to make it easy for you to specify your probabilities for a Bayesian Network.

  • With the Standard Assessment Tool, you can specify full and causally independent probability distributions.
  • With the Asymmetric Assessment Tool, you can avoid specifying redundant probabilities.
  • If you have sufficient data and use machine learning tools to create Bayesian Networks, you can use MSBNx to edit and evaluate the results.

Use It in Programs

[Excerpt from MSBN3 component object model]MSBNx is fully component based. Its most important component is MSBN3, an ActiveX DLL. MSBN3 offers an extensive COM-based API for editing and evaluating Bayesian Networks. You'll find MSBN3 especially easy to use from COM-friendly languages such as Visual Basic and JScript.

MSBNx also includes graphical components, for example, both the Standard Assessment and Asymmetric Assessment tools are ActiveX controls and can be used in other applications.

Also, you can extend the editing and evaluation abilities of MSBNx by creating add-ins. For example, MSBNx ships with an add-in for editing and evaluating Hidden Markov Models.

More Information about MSBNx

You can read about MSBNx in this tech report:

C.M. Kadie, D. Hovel, and E. Horvitz. MSBNx: A Component-Centric Toolkit for
Modeling and Inference with Bayesian Networks. Microsoft Research Technical Report MSR-TR-2001-67, July 2001. (Word format, PDF format)

You may also wish to peruse the comprehensive manuals for MSBNx

An extensive manual documents MSBNx.

A comprehensive manual documents MSBN3.

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More Information


See the end-user license agreement (EULA) for limitations of liability and support.