Female sex workers (FSW) often have a disproportionately high prevalence of HIV infection and they, along with their clients, are considered a core group contributing to the transmission of HIV in many countries. In 2010, females who reported having vaginal/anal/oral sex in the last 6 months with a male in exchange for money or gifts, aged ≥15 years, and living in Mauritius were recruited into a survey using respondent driven sampling. Consenting females (n = 299) completed a behavioral questionnaire and provided venous blood for HIV, HCV and HBV testing. HIV seroprevalence among FSW was 28.9 % and 43.8 % were infected with HCV; among HIV seropositive FSW, 88.2 % were also infected with HCV. Almost 40 % of FSW reported injecting drugs sometime in their lives and 30.5 % of all FSW reported doing so in the previous 3 months. Among those who ever injected drugs, 82.5 % did so in the past 3 months and among those 60 % reported injecting drugs at least once a day. Among FSW who ever injected drugs, 17.5 % reported sharing a needle at last injection. Regression analyses found injection drug use behaviors to be positively associated with HIV seroprevalence. These findings indicate that FSW, especially those who inject drugs, are at high risk for HIV and HCV infection and transmission and illustrates the need for gender responsive HIV and injection drug use prevention and treatment models that respond to the unique situations that affect this population.