Twelve patients on haemodialysis for 6 months to 3 years contracted AgHBs positive hepatitis, 9 being also Ag e positive. They continued to carry the same antigens. Histological surveillance was begun from the 6th month of the disease onwards, with 2 to 4 repeated biopsies in 1,5 to 3,5 years in 9 patients, the last 3 having only one biopsy between the 8th and the 15th month. In 6 patients, the first biopsy revealed chronic persistent hepatitis (CPH) and in other 6 (5 male and 1 female) chronic aggressive hepatitis (CAH). Subsequent biopsies revealed cirrhosis in a patient treated with alphamethyldopa (Ag e +), the absence of any changes in 7 other patients (4 CPH including 3 Ag e + and 3 CAH including 2 Ag e +), and an improvement in the last. Long term surveillance of hepatitis B by repeated biopsies in haemodialysed patients reveals that histological lesions are stable at 2 years, that certain drugs may have an aggravating role and that Ag e has no prognostic value.