The recent syphilis epidemic in the United States has been linked to cocaine abuse. The goal of this study was to estimate the prevalence of newly diagnosed latent syphilis, as well as previously treated syphilis, in emergency department patients giving a history of cocaine use. Charity Hospital emergency department patients without symptoms of sexually transmitted disease (STD) who admitted to cocaine use were enrolled and screened for syphilis with the automated reagin test (ART). Patients were questioned about past syphilis episodes, sexual behavior, and drug use patterns. Reactive ARTs were confirmed with the microhemaggluination antibody to Treponema pallidum (MHA-TP) or the fluorescent treponema antibody-absorbed (FTA-ABS) test. Additionally, treponemal tests were performed in 68 of 79 ART-negative patients. Twenty-four women and 78 men were included in the sample over the 6-month period from December 1989 through May 1990. Of those enrolled, 64% used crack, only 24% were exclusively intra-venous users. and 6% were exclusively nasal users. The remaining 6% utilized multiple routes of drug administration. Nine latent syphilis patients (8.8%) were diagnosed and an additional 20 (19.6%) patients were found to have had previous syphilis. among the 24 women studied, 5 (20.8%) had latent syphilis. Fifty-eight percent of women had either latent or previous treated syphilis as compared to 19% of men (P=0.0006). These data suggest that elicitation of a history of cocaine use from urban hospital emergency department patients may be helpful in identifying patients with latent syphilis. Detection and treatment of latently infected women in this setting could prevent a significant number of congenital syphilis cases.