During 1987 and 1988, samples of serum were collected from 1097 members of the staff of four prefectural hospitals in Miyazaki prefecture and from 183 acupuncturists in Fukuoka City, Japan. The staff included both surgical and non-surgical doctors, radiographers, physiotherapists, nurses, laboratory technicians and others. The samples were tested for the following hepatitis C virus (HCV) markers; antibodies to c100 (anti-c100) by means of enzyme-linked immunosorbent assay (ELISA) with supplementary recombinant immunoblot assay as well as antibodies to the GOR epitope (anti-GOR), also by means of ELISA. Anti-c100 was present in 1.7% of the doctors, radiographers and physiotherapists, in 1.3% of the nurses and in 2.2% of the acupuncturists. These prevalences were slightly higher than those in the controls but the differences were not statistically significant. Anti-c100 was not detected in any laboratory technician or other member of the hospital staff. For an accurate determination of the prevalence of HCV infection, the combined rate of anti-c100 and/or anti-GOR was also calculated. The combined prevalence of HCV infection was 4.3% in medical staff, 2.2% in nurses and 5.5% in acupuncturists. The prevalence of HCV infection among those with direct contact with patients was higher than that of the controls but without statistical significance. In the cohort we examined, the occupational risk of HCV infection was low.