Hepatitis B virus (HBV) is strongly associated with an aggressive type of chronic active liver disease (CALD) and hepatocellular carcinoma, which tend to present in the relatively young, in sub-Saharan Africa. It is known that co-existent infection with HDV tends to aggravate the course of HBV-associated liver disease. This study was carried out to determine the sero-prevalence of hepatitis D virus (HDV) among thirty one consecutive southwestern Nigerians with HBsAg-positive, HCV antibody-negative chronic liver disease. Alongside, we tested for HBsAg and the HDV antigen in fifty randomly selected sera each from blood donors and university freshmen undergoing pre-admission medical tests and who had no clinical evidence of liver disease. The HDV antigen (HDVAg) was found in the sera of two of 31 (6.5%) patients. Among the blood donors and university freshmen, HBsAg prevalence was twelve and eight per cent respectively, while HDVAg was present in none. In addition, liver biopsies of 28 other patients were stained for HDVAg. None of these was positive. These findings show that HDV prevalence is low in our community, and suggest that the virus might play only a minor role in the pathogenesis of HBsAg-associated chronic liver disease among our patients. A review of reports on the epidemiology of HDV in sub-Saharan Africa shows a rather complicated pattern that makes its impact on HBsAg-associated CALD difficult to assess. More studies designed to elucidate this pattern of HDV epidemiology are called for.