Seventy-seven chronic hemodialysis patients were vaccinated against hepatitis B virus with an intramuscular (im) hepatitis B vaccine (HBV), 40 micrograms at 0, 1, 2, and 6 months. Fifty-seven patients (74%) developed antibodies (anti-HBs). The im-responsive patients were significantly younger than the nonresponsive patients (P < 0.05). Nineteen of the 20 im nonresponders received HBV intradermally (id), 5 micrograms every 2 wk until anti-HBs developed; the 20th patient died before receiving the id vaccine. Three patients were lost to follow-up. Fifteen (94%) of the 16 developed anti-HBs after 5.2 +/- 4.7 months. The peak anti-HBs titers were 726 +/- 426 (im) and 211 +/- 260 (id) IU/L (P < 0.05). Twelve (21%) of the 57 im-responsive patients and 8 (53%) of the 15 id-responsive patients had anti-HBs less than 20 IU/L at 18 and 8 months postvaccination, respectively (P < 0.05). Further preliminary data indicate that more prolonged id vaccination can increase both the titer and the duration of anti-HBs in im-nonresponsive patients.