The prevalence of untreated sexually transmitted diseases (STDs) was assessed in a cohort of 372 sexually active inner-city women (92% black, 49% US-born) with no history of injection drug use who were recruited in Brooklyn, New York, in 1990 and 1991. The presence of STDs was assessed via culture, serologic analyses, and medical history. Sexual and drug-use histories were obtained, as was a urine sample for toxicologic analysis. Thirty-five percent of the women had at least one STD (27% Trichomonas vaginalis, 6.8% Chlamydia trachomatis, 5.2% syphilis, 2.4% human immunodeficiency virus (HIV), and 1.4% Neisseria gonorrhoeae). US-born women were more likely than foreign-born (96% Caribbean) women to have an STD (50% vs. 22%; p < 0.001). Among US-born women, 61% of crack and/or cocaine users had an STD as opposed to 34% of non-users (OR = 2.9, 95% CI 1.6-5.5). Recent crack cocaine use was the strongest predictor of syphilis infection (OR = 12.8, p = 0.019), and was reported by each of the seven HIV-positive women. This study, based on a large sample with laboratory confirmation of both STDs and drug use, documents that women who use crack cocaine are at substantially higher risk of contracting an STD than other women. STD/HIV prevention programs in inner cities should target US-born women, particularly crack cocaine users.