Abstract: Objective To understand HIV/AIDS related high risk sexual behaviors and its related factors among hero in users in Shanghai.Methods Totally 547 heroin users recruited from three Compulsory Treamtent Centers and one Volunta ry Drug Abuse Treamtent Center were interviewed.Information on HIV/AIDS knowledge,condom use attitude,and per ceived vulnerability to HIV/AIDS infection were collected and analyzed.Results High risk sexualbehaviors including non condom use sexual behavior and multiple sexual partners were very common in the heroin users,and the gender differences were found among these variables(P < 0.001).Regression results showed that male(odds rationOR=3.913,95% confi dence intervalCI=2.429-6.305) and low condom use attitude(OR=0.950,95%CI=0.910-0.991)) were the strong predictors of HIV/AIDS related risk sexual behaviors.Conclusion Comprehensive intervention strategies for reducing HIV/AIDS related risk sexual behaviors should be considered and the gender-specific factors also should be included in the intervention strategies.