A safety and immunogenicity trial was conducted in vaccinia-immune and vaccinia-naive human immunodeficiency virus (HIV)-uninfected adults who were randomized to receive 106 or 107 TCID50 of canarypox (ALVAC) vector expressing HIV-1(MN) gp160 or 105.5 TCID50 of ALVAC-rabies virus glycoprotein control at 0 and 1 or 2 months and ALVAC-gp160 or 50 μg of HIV- 1(SF2) recombinant (r) gp120 in microfluidized emulsion at 9 and 12 months; others received rgp120 at 0, 1, 6, and 12 months. All vaccines were well- tolerated. Neither vaccinia-immune status before vaccination nor ALVAC dose affected HIV immune responses. HIV-1(MN) and HIV-1(SF2) neutralizing antibodies were detected more often (100%) in ALVAC-gp160/rgp120 recipients than in recipients of ALVAC-gp160 (<65%) or rgp120 (89%) alone. ALVAC- gp160/rgp120 also elicited more frequent HIV V3-specific and fusion- inhibition antibodies, antibody-dependent cellular cytotoxicity, lymphoproliferation, and cytotoxic CD8+ T cell activity than did either vaccine alone. Trials with ALVAC expressing additional HIV components and rgp120 are underway.