OBJECTIVES: Male circumcision is associated with reduced risk of HIV infection. This may be partly because of a protective effect of circumcision on other sexually transmitted infections (STI), especially those causing genital ulcers, but evidence for such protection is unclear. Our objective was to conduct a systematic review and meta-analyses of the associations between male circumcision and infection with herpes simplex virus type 2 (HSV-2), Treponema pallidum, or Haemophilus ducreyi. METHODS: Electronic databases (1950-2004) were searched using keywords and text terms for herpes simplex, syphilis, chancroid, ulcerative sexually transmitted diseases, or their causative agents, in conjunction with terms to identify epidemiological studies. References of key articles were hand searched, and data were extracted using standardised forms. Random effects models were used to summarise relative risk (RR) where appropriate. RESULTS: 26 articles met the inclusion criteria. Most syphilis studies reported a substantially reduced risk among circumcised men (summary RR = 0.67, 95% confidence interval (CI) 0.54 to 0.83), although there was significant between study heterogeneity (p = 0.01). The reduced risk of HSV-2 infection was of borderline statistical significance (summary RR = 0.88, 95% CI 0.77 to 1.01). Circumcised men were at lower risk of chancroid in six of seven studies (individual study RRs: 0.12 to 1.11). CONCLUSIONS: This first systematic review of male circumcision and ulcerative STI strongly indicates that circumcised men are at lower risk of chancroid and syphilis. There is less association with HSV-2. Potential male circumcision interventions to reduce HIV in high risk populations may provide additional benefit by protecting against other STI.