We carried out a study to determine the seroprevalence of HBV and HCV infections in HIV positive patients at a main referral center for HIV/AIDS in Iran. Serum samples from 201 HIV positive patients referring to a referral center for HIV/AIDS were analyzed for the presence of some hepatitis B (HBsAg, anti-HBc, anti-HBs) and Hepatitis C (anti-HCV) markers, during 2004- 2005. HBsAg was positive in 27 patients (13.4%), anti-HBc was positive in 60 patients (29.8%) and anti-HBs in 23 patients (11.4%). Anti-HCV Ab was positive in 135 of 201 (67.2%). HBV and HCV coinfection was observed in 73 of 201 (36.3%). The maximum prevalence of HBV-HIV and HCV-HIV coinfections were seen in intravenous drug users; 61.2% and 85.1%, respectively (P