Despite the central role played by female intravenous drug users (IVDUs) in the worsening AIDS statistics of states in the northeastern United States, the relative paucity of research into the HN risk behaviors -particularly risky needle practices -of female drug injectors has left significant gaps in researchers' understanding of how and to what extent such women may differ in their risks from their better-studied male counterparts. This study, derived from a sample of 769 out-of-treatment lVDUs residing in an area (Paterson, New Jersey) characterized by high levels of AIDS and HIV infection among drug users, attempts to address this lacuna in the research literature by comparing the drug usage, AIDS knowledge, and needle and sexual behaviors of male and female IVDUs that place them at risk for HIV infection. In this sample, gender was found to be unrelated to HIV serostatus, injection frequency and injected drug of choice, and to most dimensions of knowledge about AIDS and the means of HIV transmission. Overall, it appears that the average Paterson female IVDU may be at greater risk for HIV infection as a result of involvement with a drug-using sex partner than because of especially risky needle practices, for females in this sample were significantly more likely than males to report injecting with a sex partner in the previous 6 months, and female IVDUs with one sex partner were more than twice as likely as males with one partner to report that this individual was an IVDU. Condom use was relatively rare, particularly among those with one partner. Moreover, female lVDUs were significantly more likely than males to be daily users of crack cocaine, and significantly more likely to report poorer health. However, current needle and sexual practices were found to be unrelated to HIV seropositivity among both males and females. In logistic regression analysis, only length of IV drug involvement was found to be independently associated with HIV seropositivity for both sexes. Implications of the data for future prevention efforts aimed at female IVDUs are discussed.