Barrett's esophagus is associated with reflux disease and substantially increases the risk of esophageal adenocarcinoma. The authors undertook a systematic review and meta-analysis of the sex ratio for Barrett's esophagus, erosive reflux disease (ERD), and nonerosive reflux disease (non-ERD) to compare these results with the sex ratio for esophageal adenocarcinoma. MEDLINE (US National Library of Medicine, Bethesda, Maryland) (1966-2004) and EMBASE (Reed Elsevier PLC, Amsterdam, Netherlands) (1980-2004) were searched for relevant citations with a highly sensitive search strategy. Studies to be included required a sample size of 50 or more patients and consecutive recruitment at an institute accessible by all. Stata, version 8.2, software (StataCorp LP, College Station, Texas) was used to conduct random effects meta-analyses. Excess heterogeneity was investigated by meta-regression. The Barrett's esophagus meta-analysis gave an overall pooled male/female sex ratio of 1.96/1 (95% confidence interval (CI): 1.77, 2.17/1). For ERD, the pooled male/female sex ratio was 1.57/1 (95% CI: 1.40, 1.76/1) and, for non-ERD, 0.72/1 (95% CI: 0.62, 0.84/1). All of these estimates were associated with substantial heterogeneity (I2 = 81.1%, 92.7%, and 88.8%, respectively). The meta-analysis estimates for ERD and Barrett's esophagus, while showing an excess of males, are substantially lower than similar estimates for esophageal adenocarcinoma. It is important to establish why male Barrett's esophagus and ERD patients are at increased risk of malignancy compared with females.