Among 54 patients, between 2 and 18 years of age, submitted to hemodialysis due to severe chronic renal failure, the prevalence of hepatitis B virus markers was 66.7% and that of HBsAg was 13.0%. Eighteen children, with no evidence of hepatitis B virus infection, were vaccinated. Following three vaccine injections, only 2 patients did not respond and a third one developed low anti-HBs titers. The vaccine was well tolerated. No relationship was observed between the intensity of the humoral immune response and age, sex, type of renal disease and time on dialysis. Seroconversion rates (87.5%) and geometric means of anti-HBs titers (greater than 4 000 Ausab Units) of these patients are similar to those observed following vaccination of healthy adults.