A random sample of seventy five doctors and dentists at the University College Hospital, Ibadan, Nigeria, was surveyed. They were offered anonymous testing for hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), antibodies to hepatitis B core antigen (anti-HBc) and to hepatitis C virus (anti-HCV) by enzyme immunoassay. The results suggest a high prevalence of hepatitis B virus (HBV) with a high potential of transmissibility, as well as a high prevalence of HCV infection. Most of the doctors and dentists use universal precaution for protection against viral hepatitis less than 50% of the occasions when they carry out procedures on their patients. Infection with HBV was associated with type of specialty (surgeons and dentists) and lack of HBV vaccination (p < 0.05). After logistic regression, these factors were independently associated with HBV infection (p < 0.05). Sixty (80%) of these health care workers had not received prior HBV vaccination. The unvaccinated personnel were more likely to be surgeons, dentists, less than 37 years of age and have fewer years of professional activity (p < 0.05). After logistic regression, only the fewer years of professional activity remained independently associated with lack of vaccination (p < 0.05). We conclude that to reduce the occupational exposure of HBV, universal precautions must be rigorously adhered to when doctors and dentists carry out procedures on their patients. It is necessary that these health care workers are vaccinated with HBV vaccine and the currently anticipated HCV vaccination, if not immune. No recent study exists that exclusively addresses this problem in health care workers in tropical Africa.