A cquired immunodeficiency syndrome (AIDS) results from A infection with a human immunodeficiency virus (HIV-1 or HIV-2) that eventually destroys a specific subset (CD4+) of helper T lymphocytes, so that the patient ultimately succumbs to opportunistic infections and/or certain neoplasms.<sup>1</sup>A high proportion of, and perhaps all, HIV-seropositive patients will show disease progression. Thus, of a cohort of HIV-1—positive subjects who were followed up for 3 years, 19% developed AIDS-related complex (ARC) and 26% developed AIDS.<sup>2</sup>Also, 41% of those who remained asymptomatic showed laboratory evidence of decline of immunologic status.<sup>2</sup>The only drug currently approved for the treatment of AIDS is 3'-azido-3'-deoxythymidine (azidothymidine, or AZT, now called zidovudine), which is therapeutically effective but has significant time- and dose-related toxicity.<sup>3,4</sup> Recent reports have implicated<i>reactive oxygen species</i>both in the pathogenesis of HIV infection and in some of the side effects of drugs such as zidovudine.