Prevalence of antibodies against hepatitis C virus (HCV) was evaluated using Ortho and Abbott HCV Elisa assays and the Abbott EIA Neutralization assay in 150 human immunodeficiency virus (HIV)-seropositive patients and compared with the prevalence of hepatitis B virus (HBV) and hepatitis D virus (HDV) markers. Overall prevalence of hepatitis C virus antibodies was 29.3%; significant variations were seen across human immunodeficiency virus risk factor subgroups: prevalence was 10.2% in homosexual men, 12.0% in bisexual men, 73.5% in intravenous drug users, 13.3% in blood transfusion recipients, and 16.6% in frequent travellers. Seroprevalence was higher in the 20 to 40 year-old age group and in patients stage II or III according to the Center for Disease Control classification. Prevalence of hepatitis B virus and hepatitis D virus markers (75.7% and 17.5% respectively) was analyzed according to hepatitis C virus marker status; patients with HBcAb were more likely to have antibodies against hepatitis C virus than their HBcAb-negative counterparts. Further studies are needed to investigate the influence of coexposure to human immunodeficiency virus and hepatitis C virus on liver lesions. Data from this study show that coinfection or coexposure is common.