Female STD clinic clients were categorized by report of sex partners' gender in the preceding 2 months and characterized with respect to HIV risk and STD diagnosis. Among 18,585 visits, 290 women (1.5%) reported sex exclusively with women, and 841 (4.5%) reported sex with both men and women. Relative to women reporting sex only with men, those reporting sex with both men and women reported more recent partners, sex with partners at high risk for HIV, injection drug and crack cocaine use, and exchange of sex for drugs or money. Women reporting sex exclusively with women more frequently reported prior sex with a bisexual man or an HIV-infected partner. Female STD clinic clients who report sex with both men and women may be at increased HIV risk relative to women reporting sex exclusively with men, and women who report sex only with women may be more likely to have had sex with men at high risk for HIV infection.