Background A dramatic increasing trend of HIV prevalence among men who have sex with men (MSM) was observed in China from 2000. Most previous investigations were based on convenience sampling and none of them differentiated money boys (MB) from other MSMs. The objectives of this study was to determine the prevalence of HIV infection and its risk factors among MSMs in Shenzhen, China, using approximate probability sampling methods; and to interpret HIV transmission pattern among MSMs with both phylogenetical and epidemiological information. / Conclusions The prevalence of MV infection in Shenzhen MSMs was similar to the national rate in MSMs. HIV infection and related characteristics in Mf3s and other MSMs were different, indicating that a separate analysis was necessary. TLS could provide information on venue comparisons for venue-based MSMs and RDS could recruit more hidden subjects. Results from this study suggest that venue-specific intervention approaches should be developed and provided to different venues. / Results HIV prevalence was 5.5% among MSMs in Shenzhen. A significantly lower HIV infection was observed in MBs (4.5%) compared with other MSMs (7.0%). The HIV infection rate among MSMs was 5.7% by TLS and 4.6% by RDS, which were not significantly different. Factors related to HIV infection in MSMs included syphilis infection, occupation, sexual orientation, venue for recruitment and hometown HIV prevalence. HIV rate and social-behavioral characteristics were found to vary with venues, with significantly higher rates in family clubs, parks and saunas, than entertainment venue. Molecular phylogenetical analysis showed that genetic clusters were related to receptive anal intercourse, short stay in Shenzhen, early age of first sex, and high hometown HIV prevalence. Venue-specific transmission chains were observed in 60% of the subjects. / Subjects and Methods A total of 2143 MSMs were recruited in Shenzhen from 2008 to 2009, including 1651 persons from time-location sampling (TLS) and 492 from respondent-driven sampling (RDS). A separate recruitment of MBs and other MSMs was applied in TLS surveys and a mixed sample of MSMs was applied in RDS. All subjects were interviewed and had blood tests for HIV and syphilis. HIV positive samples were further used for phylogenetic analysis. / Zhao, Jin / Adviser: Mingliang He. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 161-177). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.