To compare a sample of injecting cocaine users and crack users, assessing sexual behavior, risk for infection by HIV and its seroprevalence. 109 injecting cocaine users and 132 crack users were assessed, using the World Health Organization questionnaire from the expanded Cross-Site Study of Behaviors and HIV Seroprevalence among Injecting Drug Users and HIV serology. Data were assessed by Multiple Correspondences Analysis. Crack users showed less time of drug consumption when compared to the injecting cocaine users. Despite this fact, they had higher rates of risky sexual activity, differences in poli-consumption of drugs, and higher rates of involvement in illegal issues. HIV seroprevalence among crack users, although lower than for injecting cocaine users (7% vs. 33%) is high when compared to the general population at the same age. Sexual behavior of crack users in the studied sample may be considered a risk factor for HIV infection. Crack users have access to information on HIV/ AIDS, but do not make use of it to change risk behaviors that may expose them to HIV infection and dissemination. HIV seroprevalence among crack users (7%) is concerning, which makes it necessary to create preventive strategies for HIV infection and dissemination that are specifically directed toward this population.2926-30