This article compares the characteristics of women and heterosexual men with AIDS in New York City. The analysis was performed using the New York City AIDS Surveillance Database, namely, those 37,002 persons diagnosed from 1984 to 1993 between ages 15 and 64, excluding men who report sex with other men as their sole risk behavior. The median age at diagnosis was 34 years for women with heterosexually acquired disease, 36 years for women with a history of injection drug use, and 39 years for men, most of whom used injection drugs (p < 0.001). The proportion of women and the rate of increase of this proportion were greater among younger AIDS cases. By 1993 women comprised the majority of cases under age 30, and most of these young women had heterosexually acquired disease. For each decrease in 5-year age group under age 45, the odds of a case being a woman increased by 30% (95% confidence interval = 27, 33%) after adjustment for year. CD4 cell count reporting, and race/ethnicity. There was a somewhat greater youth-gender effect among black persons with AIDS (6% additional increase for each decrease in age group; 95% confidence interval = 3, 10%). Therefore, women are overrepresented among younger persons with AIDS, particularly persons of color. They are largely infected through heterosexual contact with men who have used intravenous drugs.