Sera of all male donors appearing at the blood bank of a regional hospital in Northwest Ethiopia in 1994 (n=1022) and 1995 (n=1164), were screened for the presence of human immunodeficiency virus (HIV-1) and treponemal antibodies. Additionally, screening for hepatitis B surface antigen (HBsAg) was carried out on 549 consecutive sera. In 1995, the crude seroprevalence of HIV-1 infection and syphilis was 16.7% and 12.8%. Seroprevalence of HBsAg was 14.4%. HIV and syphilis seroprevalence was highest in soldiers (30.6% and 20.9%) and daily workers (18.8% and 13.5%), and lowest in farmers (8% and 6.7%). However, farmers had the highest rate of HBsAg (18.8%). HIV-positive donors had an increased risk for being positive for syphilis antibodies (OR=3.69, 95% CI=2.69-4.96), but not for HBsAg (OR=0.79, 95% CI=0.361.67). The data indicate that (i) the HIV epidemic has not yet reached a plateau phase in Ethiopia, and (ii) the transmission and epidemiology of HBsAg in Ethiopia is different from that of HIV and syphilis.