From 1993 to 1995, the number of primary and secondary syphilis cases reported in Baltimore City (1990 population736,014) increased 97%, from 179 to 352 cases per year (Figure 1). To identify potential reasons for this increase, CDC, in collaboration with the Baltimore City Health Department (BCHD) and the Maryland Department of Health and Mental Hygiene, analyzed data about primary and secondary syphilis cases during 1992-1995 and about temporal trends in factors that may affect syphilis rates (e.g., partner-notification results, access to medical care, and community illicit-drug use). In addition, data were analyzed from the two public sexually transmitted disease (STD) clinics in Baltimore City. BCHD collects demographic data for all cases of reported syphilis among patients who reside in Baltimore City and attempts to interview and provide partner notification and treatment for these patients. This report summarizes the results of the analysis, which suggest the outbreak has been associated with decreases in partner notification and health department clinical services and a substantial increase in community cocaine use.