Hepatitis virus infection is a major cause of morbidity and mortality in sub-Saharan Africa. The high prevalence of hepatitis B virus (HBV) infection in this region is thought to be due to horizontal transmission during childhood. Hepatitis C virus (HCV) infection is also quite prevalent in Africa, but the epidemiology of this infection has yet to be defined. We examined the prevalence of HBV and HCV serological markers in 220 patients attending sickle-cell anaemia clinics in Benin City, Nigeria, in 228 healthy locals, and in 104 local commercial blood donors, to test the hypothesis that patients requiring blood transfusion from unscreened commercial blood donors (in this area of high prevalence for viral hepatitis) are at great risk for the acquisition of post-transfusion hepatitis. Overall, the frequency of hepatitis viraemia in blood donors was high (14% of donors were either HbsAg or anti-HCV positive). Evidence of previous exposure to HBV was common in all three study groups. Risk of HBV infection for sickle-cell patients was not clearly increased by blood transfusion. HCV exposure, however, appears related to transfusion requirement, and all Western-blot-confirmed anti-HCV-positive sicklers had a history of blood transfusion. Screening of blood products in sub-Saharan Africa is unlikely to reduce prevalence of HBV, but may minimize the risks of HCV transmission.