Hepatitis B is a frequent complication in haemodialysis patients because of their repeated exposure to blood products, and their impaired cellular and humoral response; trials with plasma-derived hepatitis B vaccine (PDV) show lower immune responses than those in healthy adults. Using a yeast-derived hepatitis B vaccine (YDV), the immunogenicity of two different dose levels (20 and 40 micrograms) and three vaccination schedules were compared in over 270 seronegative dialysis patients. Vaccination with 40 micrograms gave slightly better results than with the 20 micrograms dose. Seroconversion rates were higher with four dose, 40 micrograms vaccination schedules than a three dose schedule, and ranged from 80 to 86%. As the 40 micrograms, 0, 1, 2, 6 month schedule leads to a more rapid rise in antibody levels than the 40 micrograms, 0, 1, 2, 12 month schedule, it appears to be the most appropriate schedule in this patient group.