We tested serum samples collected in an urban setting (Yaounde) and in a rural area (Manyemen) for the presence of antibody to hepatitis C virus (HCV) (anti-HCV). Screening was done by second-generation ELISA and confirmation with second-generation RIBA. In Yaounde, anti-HCV was found in 12.5% of patients with febrile jaundice (95% CL 3.8-21.2), 5.5% of pregnant women (95% CL 3.3-7.3), 0% of children below 4 years of age, 31% of sickle cell patients (95% CL 20.2-41.8%), 1.6% of medical students (95% CL 0-4.7%) and 15.4% of prostitutes (95% CL 8.5-22.3). Only HBsAg-negative sera were tested for anti-HCV, except sera originating from subjects with febrile jaundice. In Manyemen, anti-HCV was detected in 6.4% of blood donors, 6.0% of pregnant women, 5.3% of HIV-positive subjects, 7.3% of RPR-positive and 3.9% of RPR-negative subjects. There was an increase in antibody prevalence with age. We conclude that HCV infection is common in Cameroon and that it is transmitted mainly by blood transfusion and probably by sexual activity.