Acquired immunodeficiency syndrome (AIDS) is one of the most important infectious diseases threatening the world's population today. The main aim of this study was to assess the epidemiologic features of HIV/AIDS from January 1989 to March 2007 in Hamadan province, Iran. In a cross-sectional study, epidemiodemographic characteristics of HIV/AIDS-positive patients during a period of 17 years were collected from health centers in Hamadan province. This study showed that about 1.8% of HIV/AIDS cases in Iran involved people who lived in Hamadan province. Further study is needed to determine the reasons for this. From January 1989 to March 2007, 285 individuals including 275 males and 10 females were infected with HIV in this province. The study showed that 88% of patients lived in urban areas while 12% involved a rural population. Hamadan city had the highest rate of HIV/AIDS infection and death with 191 and 33 individuals, respectively. The main transmission route was intravenous drug use with 78%. From 28 patients who were entered into the AIDS phase, only 10 patients returned to health centers to be covered under definite treatment. The establishment of the Triangular Clinic can be presented as the starting point in the organization of infected people to detect HIV/AIDS. Altogether, efforts in reducing the impact of HIV in this province to date can be considered beneficial. Continuous laboratory diagnostic strategies may lead in time to therapeutic approaches that result in appropriate outcomes.