Biological plausibility and evidence from case series indicate that an increased body mass index could be a risk factor for Barrett's esophagus. The aim of this study was to assemble and appraise the available evidence on the association of body mass index and Barrett's esophagus in a narrative approach. A systematic literature review identified a nested case-control study and 10 case-control studies, with sample sizes of between 129 and 953. Overall, cases were on average older than controls, more often male and white, but did not differ with regards to body mass index. An increased body mass index (> or =30 and > or =35 kg/m(2)) was associated with greater risk of Barrett's esophagus in four studies (odds ratio range: 2.0-4.0). These studies, however, did not adjust for symptoms suggestive of gastroesophageal reflux disease. No significant association was reported in the other six studies. To conclude, the existing evidence on the association between body mass index and risk of Barrett's esophagus relates primarily to case-control studies and is inconsistent. Gastroesophageal reflux symptoms can be a potential confounder and further research should better address this issue. Evidence from cohort studies may help shed further light on this putative association, which is of relevance to public health and cancer control.