The immunogenicity and reactogenicity of low-dose, recombinant DNA and plasma-derived hepatitis B vaccines were investigated in a prospective, double-blind, randomized, controlled trial. Volunteers(153)received either recombinant vaccine, 10 μg in 1 ml intramuscularly; plasmaderived vaccine, 2 μg in 0.1 ml intradermally or recombinant vaccine, 1 μg in 0.1 ml intradermally at 0, 30, and 150 days. Peak geometric mean concentrations of antibody to hepatitis B surface antigen at day 200 were 1094, 387, and 43 mIU/ml, respectively. By day 360, these concentrations had fallen to 346, 124, and 19 mIU/ml, respectively (P <.05 between groups both dates). Number of subjects with antibody ≥10 mIU/ml at day 200 was similar between the 10-μg recombinant and 2–μg plasma-derived groups (94% vs. 90%), while only 78% of the I-p.grecombinant group had protective concentrations of antibodies (P <.05). Erythema and induration occurred in most subjects in both intradermal groups, while pain was prominent at the intramuscular site especially after the second dose. Thus, plasma-derived vaccine, 2 μ.g in 0.1 ml intradermally, appears to be an acceptable cost-saving method for hepatitis B immunization, while recombinant-derived vaccine, 1 μg in 0.1 ml intradermally, produced less satisfactory results.