Hepatitis A is acute and usually self-limiting disease, but sometimes it can be dangerous such as in immunosuppressed patients. Purpose of this study is to investigate the prevalence of hepatitis A serology in HIV/AIDS Patients. 247 HIV positive patients from March 2005 to September 2006 were entered in this study. Participants completed questionnaires to elicit demographic, drug and sex risk information, and were (tested for hepatitis A. They were all referred to Counseling center for behavioral diseases in Imam Khomeini Hospital. Cases were chosen from volunteers with no history of jaundice or acute hepatitis. Data were analyzed by SPSS version 13 and results were compared between seropositive and seronegative groups using T test and chi square. Statistical significance was accepted at a level of P < 0.05.200 (80.98%) were male and 47 (19.02) were female. The mean age was 36 +/- 9.3. 238 (96.3%) of patients were seropositive. One hundred percent and 96% who were born in rural and urban areas were seropositive, respectively. Also, 85.7% and 96.6% who reside in rural and urban areas were seropositive, respectively. Iran is an endemic country for hepatitis A in which most people has asymptomatic infectious during childhood. According to high prevalence of hepatitis A positive serology in HIV/AIDS patients, routine vaccination seems to be unnecessary. But special sub populations like HIV infected infants should be evaluated more precisely and different approaches may be needed for them.