AIM: To investigate the prevalence and risk factors of HCV/HIVcoinfection in injection drug abusers (IDAs) in Lianshan YiAutonomous Prefecture of Sichuan province,China.METHODS: From November 8,2002 to November 29,2002,a community-based survey was conducted to investigatethe demographic characteristics,patterns of shared injectorsdevices and sexual behaviors in IDAs.Blood samples werealso collected to test HCV and HIV infection.A total of 379subjects were recruited in the study through communityoutreach and peer recruiting methods.RESULTS: Of the 379 IDAs,the HCV prevalence and HIVprevalence were 71.0% and 11.3%,respectively,andHCV/HIV coinfection was 11.3%.HCV infection was foundin 100% and 67.3% of HIV-positive and HIV-negative IDAs,respectively.HIV prevalence was 16.0% in HCV positiveIDAs while none of the HCV negative IDAs was positive forHIV.Ethnicity,shared needles or syringes and cotton inthe past 3 mo and syphilis infection were associated withHCV/HIV coinfection shown by univariate analysis usingchi-square test.Multivariate logistic regression analysisshowed that shared needles or syringes in the past 3 mo(Odds ratio=3.121,95% CI: 1.278-7.617,P<0.05) andsyphilis infection (Odds ratio=2.914,95% CI: 1.327-6.398,P<0.01) were significantly associated with HCV infection.No statistically significant association was found in univariateanalysis between sexual behaviors and HCV/HIV coinfection.CONCLUSION: Shared needles and syringes in the past3 mo and syphilis infection were significantly associatedwith HCV infection.Further sero-epidemiological prospectivecohort studies should be conducted to clarify the impact ofsyphilis and high risk sexual behaviors on HCV transmissionthrough unprotected sexual intercourse. A investigations into the prevalence and risk factors of HCV / HIV coinfection in injection drug abusers (IDAs) in Lianshan Yi Autonomous Prefecture of Sichuan province, China. METHODS: From November 8,2002 to November 29,2002, a community-based survey was conducted to investigate the demographic characteristics, patterns of shared injectors services and sexual behaviors in IDAs. blood samples werealso collected to test HCV and HIV infection. A total of 379 objects were recruited in the study through community outreach and peer recruiting methods .RESULTS: Of the 379 IDAs, the HCV prevalence and HIVprevalence were 71.0% and 11.3%, respectively, and HCV / HIV coinfection was 11.3% .HCV infection was foundin 100% and 67.3% of HIV-positive and HIV-negative IDAs, respectively. HIV prevalence was 16.0% in HCV positiveIDAs while none of the HCV negative IDAs was positive for HIV. Ethinicity, shared needles or syringes and cotton inthe past 3 mo and syphilis infection were associated with HCV / HIV coinfection shown by univa riate analysis usingchi-square test. Multivariate logistic regression analysis of the shared needles or syringes in the past 3 mo (Odds ratio = 3.121, 95% CI: 1.278-7.617, P <0.05) andsyphilis infection (Odds ratio = 2.914, 95% CI : 1.327-6.398, P <0.01) were significantly associated with HCV infection. No significant significant association was found in univariate analysis of sexual behaviors and HCV / HIV coinfection. CONCLUSION: Shared needles and syringes in the past 3 mo and syphilis infections were significantly associated with HCV infection. Future sero-epidemiological prospectivecohort studies should be conducted to clarify the impact ofsyphilis and high risk sexual behaviors on HCV transmissionthrough unprotected sexual intercourse.