Detailed questionnaires concerning alcohol and drug use, sexual practices, and medical history were completed by 301 homosexual men living in the Cleveland metropolitan area. Their sera were subsequently tested for antibodies to the human immunodeficiency virus. Fifty-six (18.6%) were seropositive. In a univariate analysis, age, drug use, and four specific sexual practices were associated with seropositivity. In a multiple logistic regression analysis, intravenous drug use and receptive anal-genital sex remained independent predictors of seropositivity.