Objective To integrate the empirical estimates of bisexual behaviour among the bridge population of men who have sex with men (MSM) in China and their HIV and syphilis prevalences stratified by sexual behaviour.

Methods The Pubmed, Chinese Biomedical, Chinese National Knowledge Infrastructure, VIP, Wanfang and Google Scholar databases were searched to January 2011 to identify relevant articles. Data of eligible citations were extracted by two reviewers. All analyses were performed using Stata 10.0.

Results Forty-nine articles (including 28 739 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. HIV prevalence among MSM engaging in sex with both men and women was significantly higher than in 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 MSM 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.