Introduction In China, sexual transmission has become the major route of HIV transmission, prevalence of HIV is rapidly increasing among China men who have sex with men (MSM). This study investigate the bisexual behaviour among MSM and explore their HIV/syphilis prevalences stratified by sexual behaviour in order to inform the development of targeted preventive strategies.

Methods The Pubmed, Chinese Biomedical (CBM), Chinese National Knowledge Infrastructure (CNKI), VIP, Wanfang database, and Google Scholar databases were searched through June 2010 to identify relevant articles. Data of eligible citations was extracted by two reviewers. All analyses were performed with Stata 10.0.

Results Fifty studies (including 28 739 total MSM subjects) met the selection criteria. Aggregated findings indicated that the estimated prevalence of bisexual behaviour among MSM in China is 31.2% (95% CI 28.1% to 34.5%). HIV and syphilis prevalences were 5.4% and 11.4%, respectively among MSM engaging in bisexual behaviour and 3.8% and 9.3% among MSM only having sex with men, in which HIV prevalence among MSM engaging in sex with both men and women was significantly higher than those who only have sex with men (OR 1.30; 95% CI 1.04 to 1.62; p=0.02).

Conclusion There is a high prevalence of bisexual behaviour among men who have sex with men in China, and bisexual behaviour is significantly associated with increased HIV infection risk. The results of this meta-analysis highlight a critical pattern of HIV transmission among MSM in China and indicate that targeted interventions aimed at encouraging safe sex practices and promoting societal and family acceptance of MSM are urgently needed.