The HIV-1 protein Vif comprises a multimerization domain that allows Vif-Vif interaction and Vif multimerization, which is important for Vif function in the HIV-1 life-cycle. A method for screening for an antagonist of Vif comprises contacting the multimerization domain of Vif with a test compound that specifically binds the multimerization domain. Antagonists identified by the screening assay inhibit Vif multimerization. The antagonists inhibit essential functions of Vif and accordingly are useful as inhibitors of HIV-1 replication.