Abstract This project, Expert system on HIV Diagnosis, is a software system tailored for use in the diagnosis of HIV symptoms and diseases. Health care facility should be accessible by all at all time. But some of the people that should access these facilities are far removed from these facilities. It would be of great necessity to provide a computerized system that will provide a complementary medical service, such as medical disease diagnosis in places where accessibility is a problem as well as health care facilities where qualified experts are lacking, hence this topic, Expert System on HIV and AIDS Diagnosis. The software is an expert system with a database containing expert knowledge. The user only uses it to determine whether he or she has any of the diseases within its domain. The software has been designed to be interactive with audio capability eliciting from the user if they have symptoms of the diseases. The user response helps the expert system to determine the level at which the disease is present. The user is further advice on what next to do. This software is implemented in visual basic programming environment and Microsoft database.