Patients with end-stage renal disease (ESRD) are at high risk of hepatitis B infection. Only 50-60% of the patients respond adequately to the routinely performed intramuscular (i.m.) hepatitis B vaccination. We examined whether low dose intradermal (i.d.) application of the vaccine is equivalent to regular i.m. administration. Thirty-two patients with ESRD of different etiologies were investigated at the onset of dialysis treatment [11 patients on continuous ambulatory peritoneal dialysis (CAPD) and 21 patients on hemodialysis (HD)]. Patients were vaccinated at month 0, 1, 3 and 6 with either 40 micrograms HBs Ag (2 ml Engerix B, 14 patients) i.m. or with 10 micrograms HBsAg (0.5 ml Engerix B, 18 patients) i.d. The i.m. vaccination was applied in the deltoid muscle, while for i.d. vaccination the vaccine was injected into the skin of the deltoid region. Six weeks after the last vaccination anti-HBs titers were measured. 61% (11 patients) of the patients vaccinated i.d. and 64% (9 patients) of the patients vaccinated i.m. developed protective titers. Neither the height of the titers nor the proportion of patients responding to the vaccination differed significantly between the two vaccination schedules. No difference regarding the height of titers achieved or the rate of seroconversion could be found when CAPD and HD patients were analyzed separately. Only minor side effects have been observed. According to these preliminary data i.d. hepatitis B vaccination in patients with ESRD may be equivalent to i.m. administration of the vaccine. Given equivalency i.d. vaccination may be a cost-saving alternative to i.m. vaccination (only a quarter of the dose of i.m. administered vaccine is needed) with a good practicability (vaccination can be performed during HD) and a low rate of side effects.