The epidemic of acquired immune deficiency syndrome (AIDS) and its causative agent, the human immunodeficiency virus (HIV), are serious and spreading. In response to the epidemic, a variety of intervention and prevention programs have been instituted. In such AIDS intervention and prevention (AIP) activities, the role played by information systems becomes more and more important. The applications of information systems technology in AIP mostly seem to fall within a spectrum of databases, decision support systems and expert systems. This paper describes the implementation of an information system in a regional AIDS intervention and prevention program. In this integrative information system, the database is integrated with both decision support systems and expert systems, and decision support systems are integrated with expert systems. The implementation results of the system present evidence of the usefulness of the system in AIDS intervention and prevention.