Hepatitis A and B virus infections are common in the tropics. There is, however, no information concerning hepatitis A virus (HAV) infection in Cameroon, while data on the hepatitis B virus (HBV) infection are incomplete. Sera from 272 subjects attending the Central Hospital, Yaoundé, for blood donations or mild ailments were tested by an ELISA technique for the presence of anti-HAV total antibody; antibody was found in 217 (79.8%). When 188 subjects (randomly chosen from the 272) were further tested for the presence of the hepatitis B surface antigen (HBsAg), 18 (9.6%) were positive; these included 9 of 127 males (7.1%) and 9 of 61 females (14.8%). Antibody to the HBsAg (anti-HBs) was present in 15 of 43 persons (34.9%) who were HBsAg-seronegative, while antibody to the hepatitis B core antigen was detected in 76 of 97 subjects (78.4%) who had been seronegative to the HBsAg and had not been tested for anti-HBs. Thus, 60% of our subjects (including 45% of subjects under five years of age) had at least one marker indicative of previous infection with the hepatitis B virus.