The apparent detection of human immunodeficiency virus (HIV-1) DNA by the polymerase chain reaction (PCR) in seronegative individuals has been the subject of great concern. In this study, 324 seronegative participants in the San Francisco Men's Health Study were evaluated for evidence of infection using a PCR testing algorithm with multiple amplifications targeting different regions of the HIV-1 genome. While most PCR reactions were negative, 8.6% of the specimens showed weak reactivity with one or more primer sets. However, all were negative with at least one primer set and no definitively positive specimens were identified. This study addressed the possibility that some of these PCR reactions might represent latent infection or abortive exposure, leaving residual integrated DNA, rather than false-positive reactions. The frequency of such reactions was determined in homosexual men who have been at risk for HIV-1 infection and in exclusively heterosexual men who have little or no past exposure. The results demonstrate an identical frequency and distribution of equivocal PCR reactions in both populations. Assuming that there is minimal HIV-1 infection among seronegative heterosexual men in San Francisco, we conclude that PCR testing does not provide evidence for a reservoir of occult HIV-1 infection in seronegative homosexual men.