Abstract: Objective To investigate humman immunodeficiency virus（ HIV） /syphilis /hepatitis C virus（ HCV） related knowledge,behavior and infection rates among the drug users in Shenyang city. Methods A questionnaire sruvey was carried out among 400 drug users by trained medical professionals. The information on social demographic characteristics,HIV / AIDS awareness,and high risk behavior were collected and blood samples were detected for HIV / syphilis /HCV infection. Results The most of the drug users had no comprehensive knowledge about AIDS and only 50. 8% of them answered the 8 questions about AIDS correctly. Among the drug users,32. 3% had commercial sex and only 21. 7%of them used condom consistently. For the drug users 35. 0% reported intravenous drug use and 30. 7% shared syringe with others. The prevalence of HIV,syphilis,and HCV infection was 1. 0%,6. 3%,and 15. 5%,respectively. Conclusion There is a great risk of HIV transnission among the drug users in Shenyang city and HIV,syphilis,and HCV infection rates are relatively high among the drug users. Intravenous drug use,syringe sharing,commercial sex,and other risk behaviors are also prevalent.