A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was 'Does high body mass index (BMI) have any impact on survival of patients undergoing oesophagectomy for oesophageal cancer?' A total of 232 papers were found using the reported search, of which 8 papers represented the best evidence to answer the clinical question, which included 1 meta-analysis and 7 cohort studies. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. One meta-analysis and 4 cohort studies provided the evidence that high BMI was significantly correlated with a better survival of oesophageal cancer patients undergoing oesophagectomy, while the other 3 cohort studies found that high BMI had no impact on the survival of those patients. We conclude that patients with high BMI may have a better prognosis than those with normal BMI undergoing oesophagectomy for oesophageal cancer.