A man was found to have a repeatedly positive enzyme immunoassay (EIA) that was confirmed by a western blot with six positive bands. He was told that he was seropositive for the human immunodeficiency virus (HIV), but subsequent EIAs were negative and western blots were either negative or indeterminant. All other HIV-related studies were unrevealing, and no explanation for the false-positive result was found. We have not absolutely eliminated the possibility of mislabeled specimens, but we believe this to be unlikely. The possibility, albeit infrequent, of concomitant false-positive EIAs and western blots should be kept in mind when formulating public policy with regard to HIV testing.