Sexual behavioral data from a survey of 396 male drug injectors showed that 301 (76%) were behavioral heterosexuals. 49 (12.45%) were bisexuals. and 46 (11.6%) were homosexuals over the previous 5 years. Among those sexually active during the 6 months before the interview, bisexuals were similar to heterosexuals and homosexuals in reporting two or more female or male partners, respectively. Overall, almost three fourths of the bisexuals had two or more sexual partners. Bisexuals were also similar to heterosexuals in reported heterosexual anal intercourse ( 16 and 15% respectively), and to homosexuals in reported homosexual insertive anal intercourse (33 and 54%, respectively). They were less likely than heterosexuals to engage in vaginal and insertive oral sex with women and than homosexuals to practice receptive anal and oral sex with men. The three groups all practiced high levels of unprotected sex. Almost half the behavioral bisexuals identified themselves as heterosexuals. Self-identified heterosexuals in the sample were less likely than self-identified gays or bisexuals to state they reduced sexual risk; however. reported condom use was low for all three groups. With human immunodefi-ciency virus infection rates of 54% (21 of 39) for behavioral homosexuals. 24% (11 of 45) for bisexuals. and 9% (24 of 260) for heterosexuals, these findings indicate an urgent need for more effective sexual risk reduction among injection drug users and their partners.