OBJECTIVE: To understand the syphilis infection and its high risk factors among men who have sex with men (MSM) recruited from different channels. METHODS: Supported by the China-Gates Foundation HIV program from July to December 2011, we cooperated with community based organizations to conduct syphilis testing intervention among MSM from 14 cities (Beijing, Shanghai, Tianjin, Chongqing, Harbin, Shenyang, Qingdao, Xi'an, Nanjing, Wuhan, Hangzhou, Changsha, Kunming, and Guangzhou) and one province (Hainan province). Participants were recruited from different channels by the staff of local CBOs,...