Crack use has been associated with increased risk for HIV seropositivity. This study was undertaken to examine HIV-related risk behaviors among crack users in East Harlem, New York and Philadelphia, Pennsylvania, two northeastern communities which have reported extensive crack use. Crack users recruited in East Harlem (n = 1434) and Philadelphia (n = 694) were compared on demographics, drug and sex-related risk behaviors, health-related behaviors, and HIV serostatus. Many significant differences were found, and seropositivity was higher in the New York sample (25% vs. 11%, chi 2 = 36.28, p < .001). Being a recent drug injector was a significant predictors of seropositivity in both communities, and differences between communities were found in additional predictors of serostatus. Results suggest that tailored HIV interventions may be needed for different communities. In addition, aggregate data across communities, even those that may be in geographical proximity, may obfuscate differences important to incorporate in developing prevention/intervention efforts.