Background: The true influence of body mass index on the outcome of esophageal cancer surgery is unclear. The aim of this study was to determine the relation between preoperative body mass index and clinical and oncological outcomes of esophagectomy for cancer in a patient cohort from the Dutch nationwide audit. Methods: All patients who underwent esophagectomy for cancer between January 2011 and 2016 were identified in the Dutch Upper Gastrointestinal Cancer Audit. Patients were divided into 4 body mass index categories (<18.5 kg/m 2 underweight, 18.5 to 25 kg/m 2 normal weight, 25 to 30 kg/m 2 overweight, and >30 kg/m 2 obese) and were compared for clinical and oncological outcomes with the use of propensity score–matched analysis. Results: Of the patients, 2,598 were included (underweight = 70, normal weight = 1,097, overweight = 1,007, and obese = 424). Before propensity score–matched analysis, underweight patients had a significantly longer hospital stay, more chyle leakage, underwent more re-operations, and had a higher in-hospital/30-day mortality compared to the other weight groups. After propensity score–matched analysis, 560 patients were included: 62 were underweight, 180 were normal weight, 165 were overweight, and 153 were obese. Length of hospital stay, chyle leakage, necrosis of the reconstruction, re-interventions, re-operations, re-admittance to the intensive care unit/medium care unit, and in-hospital/30-day mortality were seen most in the underweight group. No differences were seen in intraoperative complications and oncological outcomes. Conclusion: Underweight patients are more prone for the development of postoperative complications after esophagectomy. Physicians and dieticians should be aware of the impact of underweight on postoperative outcome. Future studies should focus on nutritional status and the effect of preoperative correction of body weight.