The current study included a sample of 86 inner-city treatment seeking drug users, comparing risky sexual behavior (RSB) across primary users of a) heroin and not crack/cocaine, b) crack/cocaine and not heroin, and c) both heroin and crack/cocaine. To explore potential mechanisms, additional analyses also examined impulsivity across several domains as mediators of RSB and drug choice. RSB was higher in primary crack/cocaine users than in primary heroin users, with those using both drugs evidencing equal or lesser levels of RSB than crack/cocaine users. A similar pattern was found for impulsivity for several measures. Little support for any dimension of impulsivity as a mediator in the relationship between drug group and RSB was found. The current results allow insight into contextual elements that contribute to RSB across drug groups, allowing one to determine if elevated impulsivity in crack/cocaine users is due to pharmacological effects of crack/cocaine.