Methods This study includes two phases. Phase one: A cross-sectional survey was conducted among 280 female sex workers in various urban areas in Tehran. During the survey a 114 item researcher designed questionnaire was used. The validity and reliability of questionnaire was assessed during a pilot study. Phase two: Following the quantitative survey a qualitative study was done which 39 in-depth interviews were conducted to gain insights into the context of their risky sexual behaviors and suggestions for feasible HIV primary prevention interventions.