Abstract: ObjectiveTo investigate the prevalence of AIDS-related high risk behaviors among men who have sex with men(MSM)ever infected by sexually transmitted disease(STI)within previous one year. MethodsSnowball sampling and an anonymous questionnaire survey were adopted for a cross-sectional study to compare the differences in high risk behaviors related to AIDS between MSM with STI and without STI experience in nine cities.SPSS 13.0 statistical software was used in data analysis. ResultsAmong the 2 134 MSM,compared to the MSM without STI experience,the MSM with STI had a significant higher number of total sexual partners of anal sex with same sex and the number of anal sex in the previous six months,with the medians of 20.0 and 3.0,respectively.In the previous year,28.8%(95/330)of MSM with STI participated in group sex,24.7%(81/328)had commercial homosex,44.1%(146/331)reported bleeding while having sexual intercourse,with significant differences compared to those of MSM without STI.The MSM with STI had a significant lower rate of condom use(67.3%181/269) in the latest anal sex.Moreover,STI group had a higher HIV infection rate(4.03%14/347). ConclusionThe MSM with STI experience have a high prevalence of high risk AIDS-related behaviors and urgent health intervention targeting MSM with STI experience should be conducted.