One-hundred and fifteen consecutive patients with breast cancer were examined for hepatitis B. All the patients received adjuvant chemotherapy. The median age was 46 years (range 26-54 years). None of the patients were found to be HBsAg-positive. The prevalence of HbsAg was within the limits of 0-0.026 (95% confidence interval). Vaccination of patients receiving chemotherapy is not indicated. Furthermore, regular HBsAg screening among patients under 55 years cannot be recommended.