Serum samples from 201 HIV positive patients were collected to determine the seroprevalence of CMV infection in Iranian HIV infected patients during March 2004 until March 2005 using conventional ELISA kits. An antibody level of >1.1 Iu/ml was considered positive. The seroprevalence of CMV infection was 94%.The maximum prevalence of CMV antibody was seen in patients with unsafe sex and IDUs. Prevalence of CMV was much higher in patients with low socioeconomic status and low level of education. 83% of patients with CD4