Abstract: ObjectiveTo assess human immunodeficiency virus(HIV)incidence and influencing factors of HIV seroconversion among men who have sex with men(MSM)in Suzhou city.MethodsMSM were enrolled at voluntary counseling and testing clinic or referred by MSM volunteers from April 2010 to December 2012.An open prospective cohort study was conducted among HIV-seronegative MSM with the follow-ups of every six months.ResultsA total of 686 MSM were enrolled in the cohort.The average age of the MSM was 30.8 years,with a range of 19-64 years;73.9% of the MSM were unmarried;99.2% were Han Chinese;68.7% lived in Suzhou more than 2 years;and 53.6% had education of college degree or above.Of the MSM,52.8%(362/686)were followed at least once after the enrollment.The incidence rates were 4.93 per 100 person-years(PY)for HIV infection and 8.25 per 100 PY for syphilis.No hepatitis C virus(HCV)seroconversion was observed.Multiple Cox regression analysis indicated that sexually transmitted infections(STIs)within recent 12 months(adjusted hazard risk(HR)=1.77,95% confidence interval(95% CI)=1.19-2.90 and inconsistent condom use in anal sex within recent 6 months(adjusted HR=1.84,95% CI=1.14-2.95)were significantly related with HIV seroconversion.ConclusionThe HIV incidence among MSM in Suzhou is high and efforts should be focused on promotion of condom use,prevention and treatment of STIs among MSM.