A Phase I, Multicenter, Randomized Trial to Evaluate the Safety and Immunogenicity of Vaccinia-Derived MN HIV-1 Recombinant Envelope Glycoprotein (rgp160) of Human Immunodeficiency Virus at Two Different Vaccination Schedules

Inclusion Criteria Subjects must have: * Normal history and physical exam. * Negative test for HIV by ELISA within 6 weeks prior to immunization. * Negative test for HIV by Western blot. * CD4 count \>= 400 cells/mm3. * No history of smallpox vaccination. * Normal urine dipstick with esterase and nitrate. * No history of immunodeficiency, chronic illness, autoimmune disease, or use of immunosuppresssive medications. Exclusion Criteria Co-existing Condition: Subjects with the following conditions are excluded: * Positive for hepatitis B surface antigen. * Medical or psychiatric condition or occupational responsibilities that preclude compliance. * Active syphilis (NOTE: If serology is documented to be a false positive or due to a remote (\> 6 months) infection, subject is eligible). * Active tuberculosis (NOTE: Subjects with a positive PPD and normal x-ray showing no evidence of TB and who do not require INH therapy are eligible). * Eczema. Household contact with persons meeting any of the following criteria: * pregnancy, \< 12 months of age, eczema, or immunodeficiency disease or use of immunosuppressive medications. Subjects with the following prior conditions are excluded: * History of anaphylaxis or other serious adverse reactions to vaccines. * Eczema within the past year. * PER 8/94 AMENDMENT: History of cancer unless surgically excised with reasonable assurance of cure. * PER 8/94 AMENDMENT: History of serious allergic reaction requiring hospitalization or emergent medical care. Prior Medication: Excluded: * Prior HIV vaccines. * Live attenuated vaccines within the past 60 days. NOTE: Medically indicated subunit or killed vaccines (e.g., influenza, pneumococcal) do not exclude but should be administered at least 2 weeks prior to HIV immunizations. * Experimental agents within the past 30 days. Prior Treatment: Excluded: * Blood products or immunoglobulin within the past 6 months. Higher risk behavior for HIV infection as determined by screening questionnaire, including: * History of injection drug use within 12 months prior to study entry. * Higher or intermediate risk sexual behavior.