Several known antiretroviral agents were tested for their ability to inhibit the activities of human immunodeficiency virus type 1 reverse transcriptase purified from virions or from a recombinant Escherichia coli strain. The recombinant reverse transcriptase, a polypeptide of 66 kilodaltons, showed inhibition profiles indistinguishable from those of the virion-derived enzyme with all tested compounds, except for suramin and two dextran sulfates. These were more inhibitory to the recombinant enzyme, presumably because the E. coli-derived enzyme was more highly purified. The relative ease with which large quantities of recombinant enzyme can be prepared should facilitate the large-scale screening and identification of new potential inhibitors of the human immunodeficiency virus type 1 reverse transcriptase.