Patients are randomized to receive rgp120/HIV-1MN vaccine or alum adjuvant placebo by intramuscular injection at weeks 0, 4, 8, 12, 16, and 20, with or without daily oral zidovudine (AZT) or their current stable dose of antiretroviral therapy. After completing the primary vaccination series, patients are permitted to continue into an extension phase, in which they receive a booster vaccination at weeks 28, 36, and 44. Patients will be stratified by CD4 count: 350-500, 200-349, and 50-199 cells/mm3. A fourth group with counts of 350-500 cells/mm3 will serve as a pilot group and receive vaccine only.