BACKGROUND AND OBJECTIVES: Sarcopenia or loss of skeletal muscle mass has been identified as a poor prognostic factor for a wide variety of diseases and conditions. We investigated whether preoperative sarcopenia is associated with postoperative complications in patients undergoing esophagectomy for thoracic esophageal cancer. METHODS: We retrospectively reviewed the medical records of consecutive patients with thoracic esophageal cancer who underwent esophagectomy between September 2005 and July 2014 at Kyoto University Hospital. Skeletal muscle mass was assessed using preoperative computed tomographic scans by measuring the cross-sectional muscle area at the third lumbar vertebral level. RESULTS: Among the 199 eligible patients, 149 (75%) were classified as having sarcopenia. There was no difference in the incidence of overall complications between the groups (risk ratio [RR]: 1.10, 95% confidence interval [CI]: 0.80-1.53, P = 0.54). However, pulmonary complications were significantly more frequent in the sarcopenia group than in the nonsarcopenia group (RR: 2.63, 95% CI: 1.20-5.77, P = 0.007). Multivariate analyses demonstrated that sarcopenia was associated with a high adjusted risk of one or more pulmonary complications (odds ratio: 2.96, 95% CI: 1.14-7.69, P = 0.026). CONCLUSIONS: Sarcopenia independently predicts pulmonary complications after esophagectomy for thoracic esophageal cancer. J. Surg. Oncol. 2016;113:678-684. © 2016 Wiley Periodicals, Inc.