Abstract: Objective This study was conducted to determine the seroprevalence and risk behaviors for HIV, syphilis, and HCV infection among drug abusers in Suzhou City. Methods Using questionnaire to investigate 494 drug abusers about their drug using features and sexual behaviors etc, analyzing their anti-HIV, anti-HCV and syphilis serology test from July to December, 2006. Results The drug abusers, mesculine of anti-HIV was 2.43%, anti-HCV 21.05%and syphilis serology test 3.44%. We found the HIV using injection and sharing needle with other people. The infection rate of HCV are higher in intravenous drug users(IDUs)than non-injection drug users. 4.25%had commercial sexual behavior, of which 14.29% used condom each time. Conclusion Our data suggest a high prevalence of HCV infection among IDUs in Suzhou associated with needle-sharing behaviors. HIV seroprevalence appears to be similar with the average level of China. Risk sexual behavior increase the danger to spread AIDS、HCV and syphilis from the drug abusers to the other. Proper intervention must be taken to prevent these diseases.