Abstract: Objective To investigate epidemiological and clinical characteristics of first diagnosed human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) patients receiving highly active antiretroviral therapy (HAART) in Xi'an city.Methods Medical records of 1 243 HIV/AIDS patients first diagnosed and receiving HAART at Xi'an Municipal Infectious Disease Hospital from 2005 through 2013 were collected and analyzed retrospectively.Results The majority of the patients were young and middle-aged males and were infected through homosexual contact.Of all the HIV infections,324 (26.06%) showed clinical symptoms of AIDS,with signs of common opportunistic infections including fever,persistent diarrhea,thrush,skin lesion,and Pneumocystis jiroveci pneumonia; body mass index,hemoglobin,and count number of CD4,CD8 and white blood cells were significantly decreased with the severity of the AIDS (all P<0.01) and there was a close relationship between CD4 count and the incident of opportunistic infections among the AIDS patients.Conclusion Various opportunistic infections should be treated in time and close attention should be paid to the changes in CD4 and CD8 count among AIDS patients.