Background: Besides HIV and syphilis, hepatitis C virus (HCV) is also rapidly spread among men who have sex with men (MSM). This study was designed to identify the prevalence of these 3 sexual transmitted diseases in MSMs in Shenzhen, China. Methods: A cross sectional study was conducted by using time location sampling method from April to July, 2008. 831 MSM participants (including 454 Male sex workers) were recruited and finished guided self-administered questionnaires (or interviews if they have difficulty in reading or understanding) in 37 venue-date-time randomly selected from 48 active venues. Results: Results were analyzed using SPSS. 736 blood samples were collected for HIV, syphilis and HCV test. Participated MSMs were between the age of 18 to 51 years (25.5±5.9) with a majority of 20-29 years (73.7%). Most of them finished junior high school education (74.9%). 84.2% had high level of knowledge on modes of transmission and prevention. Likewise, 56.0% MSMs have ever sold sex to men, 38.3% of them were self identified as gay, 35.1% as bisexual. 78.3% MSMs had multiple male sexual partners and 50.3% MSMs always used condom. 48.6% of them had sex with women in the past 6 month, and the condom use rate decline to 35.1% during both male and female sex. HIV positive rate is of 6.7% and syphilis for 18.3%, HCV is only found in 3 cases (0.4%). Conclusions: A greater number of the participants have both male and female sex partners. This survey shows that HCV infection rate is still low among MSMs in Shenzhen, although the HIV and syphilis rate is high and continuing increased in the past few years.