Diagnosing HIV-patients and prescribing the correct drug regimen can be a complex task whose outcome is dependent on a large number of variables. The cost of an incorrectly administered drug, even for a very short time, can be enormous. In this paper, the implementation of an interactive expert system to diagnose HIV patients that runs on World Wide Web clients is discussed. The system is managed centrally and accessed either as part of an Intranet, or as an Internet site. The issues related to the implementation of the expert system are presented, the interfacing of the original code to the WWW is briefly described, and the database interface used for maintaining patient records are discussed.