OBJECTIVE Postoperative complications after thoracic esophagectomy are common and sometimes life-threatening. Optimized perioperative nutrition is essential for patient well-being and recovery. In this paper, we assessed the effects of perioperative parenteral nutrition on the nutritional status of thoracic esophagectomy patients. METHODS The nutritional status of 25 patients, undergoing either 2- or 3-field lymph node dissection, was evaluated from one day before surgery until 14 days after. Respiratory quotient and energy expenditure were measured by indirect calorimetry. Nitrogen balance was measured as the difference between urophanic and intake nitrogen. We also measured nitrogen loss, total cholesterol, cholinesterase, total protein, rapid turnover protein, and biomarkers that included prealbumin, transferrin, and retinol-binding protein. RESULTS We observed significant and negative differences between pre- and postoperative calorie intake, caloric balance, respiratory quotient, nitrogen loss, nitrogen balance, total cholesterol, cholinesterase, total protein, and retinol-binding protein. On postoperative days 1-3, calorie intake was insufficient and caloric balance became negative and significantly lower than that before surgery. CONCLUSIONS Parenteral nutrition provides insufficient nutrients to thoracic esophagectomy patients. Preoperative nutrition and early postoperative enteral nutrition in combination with parenteral nutrition may improve nutritional status, particularly in the early stages after surgery.