Abstract: ObjectiveTo investigate the distribution characteristics and factors associated with syphilis-HIV co-infection among men who have sex with men(MSM)in Shenzhen city. MethodsSyphilis/HIV surveillance data were collected among MSM from 2005 to 2011 in Shenzhen and analyzed with Cochran-Armitage trend test and logistic regression. ResultsA total of 5 232 MSM receiving voluntary counseling and testing were enrolled in the study.The infection rate of syphilis,HIV,and syphilis-HIV co-infection among the MSM was 20.97%,6.46%,and 3.56%,respectively.The positive rate of syphilis-HIV co-infection increased gradually from 2005 to 2011(Z=-3.7359,P=0.0002).The results of multivariate logistic regression analysis showed that syphilis-HIV co-infection was significantly associated with age,education level and role in homosexual behavior.The relative risk of syphilis-HIV co-infection for the MSM aged greater than or equal to 40 years was 2.165(odds ratio OR=2.165)compared with those less than 40 years.The relative risk of syphilis-HIV co-infection for the MSM with high school education and college or above education was 0.714 and 0.522(OR=0.714 and OR=0.522)compared with those with junior school or below.The relative risk of syphilis-HIV co-infection for the MSM mainly with insertive anal sex and with both receptive and insertive anal sex was 0.388(OR=0.388)and 0.606(OR=0.606)compared with those mainly with receptive anal sex. ConclusionThe prevalence rate of syphilis-HIV co-infection showed a statistically significant increase from 2005 to 2011 and it is urgent to control and prevent syphilis/HIV oc-infection among MSM in Shenzhen.