Several studies have shown a high prevalence of HIV-seropositive status among crack users, though most refer to North American populations. Few studies evaluate HCV prevalence among female crack users. In addition, there is a particular lack of data about risk behaviors and HIV/HCV prevalence in this population around the world. In order to ascertain the HIV/HCV serostatus and associated risk behaviors for infection of female crack users of Porto Alegre, Brazil. A cross-sectional study of a convenience sample of 73 current female crack users was conducted. Subjects answered NIDA’s Risk Behavior Assessment and an AIDS Information Questionnaire. In addition, blood was collected from subjects for HIV/HCV tests. The overall prevalence of HIV was 37.0%; HCV seroprevalence was 27.7%; of 15.1% the sample was co-infected with HIV and HCV. Four years of schooling or fewer (OR 4.72–CI 95%; 1.49–14.99) and having three or more HIV tests in one’s lifetime (OR 4.26–CI 95% (1.29–14.04)) were associated with HIV infection (after multivariate logistic regression). The single greatest risk factor for HCV infection was having 4 years of schooling or fewer (OR 4.51–CI 95%; 1.18–17.27). We found a very high prevalence of HIV and HCV infection among female crack users, and low education was the most significant risk factor associated with both infections.