Subjects (n=11,435 males and n=5,636 females) were part of the National Institute on Drug Abuse AIDS Cooperative Agreement study. For males, bisexuality was highly associated with being homeless, having ever been paid for sex, having five or more sex partners in the month preceding the interview, having an IV drug-using sexual partner in the month preceding the interview, using crack, and sharing injection equipment in the month preceding the interview. For females, bisexuality was associated with ever having been arrested, past substance abuse treatment, ever having been paid for sex, ever having paid for sex, having five or more sexual partners in the month preceding the interview, ever using cocaine, and sharing injection equipment in the month preceding the interview. Both male and female bisexuals, when compared to heterosexuals, were at higher risk for HIV and were more likely to be HIV positive. One implication of these results is that a universal prevention message may not be as effective as targeting prevention messages specifically for bisexual males and females. Tables, note, references