We examined the relationships among sexual self-identity, sexual and drug use behaviors, and human immunodeficiency virus (HIV) infection among a sample of 224 male street prostitutes. Structured interviews were administered, and blood samples were collected and tested for HIV, syphilis, and hepatitis B. The sample included 17.9% homosexual, 46.4% heterosexual, and 35.7% bisexually identified men. Congruence between the prostitutes' non-paid sexual behavior and their sexual self-identification were closest for the heterosexual and homosexual identified men. The significant demographic and occupational differences between the prostitutes in each sexual self-identity category included education, history of physical abuse, homelessness, and geographical mobility. Based on self-identification, the rate of HIV infection was 50% for the homosexuals, 36.5% for the bisexuals, and 18.5% for the heterosexuals. The differences in HIV infection rates between the men of each sexual self-identity category were significantly related to self-reported receptive anal sex, number of non-paid sexual partners, cocaine use, injection drug use, acquaintance with a person with AIDS, history of syphilis, and history of hepatitis. Sexual self-identity was not a significant predictor of HIV serostatus.