OBJECTIVES. This study compares characteristics, behaviors, and human immunodeficiency virus (HIV) infection in women who reported same-sex contact and women who had sex only with men. METHODS. Participants were patients attending a New York City sexually transmitted disease clinic. Structured questionnaires were administered by interviewers. RESULTS. Overall, 9% (135/1518) of women reported same-sex contact; among these, 93% also reported contact with men. Women reporting same-sex contact were more likely than exclusively heterosexual women to be HIV seropositive (17% vs 11%; odds ratio [OR] = 1.7, 95% confidence interval [CI] = 1.0, 2.6), to exchange sex for money/drugs (48% vs 12%, OR = 6.7, 95% CI = 4.6, 9.8), to inject drugs (31% vs 7%, OR = 6.3, 95% CI = 4.1, 9.5), and to use crack cocaine (37% vs 15%, OR = 3.3, 95% CI = 2.2, 4.8). HIV in women reporting same-sex contact was associated with history of syphilis (OR = 8.8), sex for crack (OR = 5.7), and injection drug use (OR = 4.5). CONCLUSIONS. In this study, women who reported same-sex contact were predominantly bisexual. They had more HIV risk behaviors and were more often HIV seropositive than women who had sex only with men. Among these bisexual women, heterosexual contact and injection drug use were the most likely sources of HIV. There was no evidence of female-to-female transmission.