This invention provides a composition for inhibiting HIV-1 infection comprising at least two compounds in synergistically effective amounts for inhibiting HIV-1 infection, wherein at least one of the compounds prevents the productive interaction between HIV-1 and an HIV-1 fusion co-receptor. This invention also provides a composition which inhibits fusion of HIV-1 or an HIV-1 envelope glycoprotein.sup.+ cell to a target cell, comprising at least two compounds in synergistically effective amounts for inhibiting fusion of HIV-1 or an HIV-1 envelope glycoprotein.sup.+ cell to a target cell, wherein at least one of the compounds prevents the productive interaction between HIV-1 and an HIV-1 fusion co-receptor. This invention also provides a method of treating a subject afflicted with HIV-1 which comprises administering to the subject an effective dose of said compositions. This invention also provides a method of preventing a subject from contracting HIV-1 which comprises administering to the subject an effective dose of said compositions. This invention also provides an anti-CCR5 monoclonal antibody selected from the group consisting of PA8, PA9, PA10, PA11, PA12, and PA14.