en Infectious Disease Infectious Disease Original Research Original Research <p> <strong> Background: </strong>HIV/AIDS patients are mainly hospitalized for HIV-related diseases and opportunistic infections. Thisstudy was performed todetermine thecauses ofhospitalization and its related factors in HIV/AIDS patients in Tehran’s Imam Khomeini Hospital during 2009-2012. </p><p> <strong> Methods: </strong>Thisstudy wasa descriptive cross-sectionalstudy . HIV patients admitted to the Imam Khomeini Hospital were included in the study through censusmethod, during the study. Demographic variables, hepatitis co-infection, CD4 count, history of receiving anti- retroviral therapy (ART), cause of admission, length of hospitalization and patient's outcome were recorded . Data were analyzed by SPSS software and by means of Chi-square and Mann Whitney U tests . </p><p>  <strong>Results: </strong>Duringthe study,555HIV patientswere included in,84.9 % of whom were male, with the mean age of 36.59±8.51years and the average length of hospitalization for 16.04±18.82 days. </p><p>  Opportunistic infections were the most common cause of hospitalization (46.5%) with prevalent of which was pulmonary tuberculosis being the most prevalent (37.6%). </p><p>  Patientssuffering fromopportunistic infectionshadsignificantlylowerCD4countand longer hospitalizationthan theother diseases. </p><p>  A significant difference was detected between patients outcome and the history of ART. </p><p>  <strong>Conclusion: </strong>Low CD4 count may contribute to an increase in number and length of hospitalization in HIV/AIDS patients. Accordingly, it appears to affect outcome of their treatment and ART was accompanied by a drop in the death rate of hospitalized patients. </p> HIV Infection, AIDS, Hospitalization, Opportunistic infections, ART. 431 437 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-718&slc_lang=en&sid=1 Mahboobeh Hajiabdolbaghi hajiabdo@tums.ac.ir 200319475328460012709 200319475328460012709 No Department of Infectious and Tropical Diseases, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran. Sirous Jafari jafari_sirous@yahoo.com 200319475328460012710 200319475328460012710 No Department of Infectious and Tropical Diseases, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran. Sedighe Mansouri sedighehmansori@yahoo.com 200319475328460012711 200319475328460012711 No Department of Infectious and Tropical Diseases, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mojtaba Hedayat Yaghoobi hyaghooby@razi.tums.ac.ir 200319475328460012712 200319475328460012712 Yes Department of Infectious and Tropical Diseases, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran.