Thoracic surgery creates a different environment from abdominal surgery in respect to the surgical procedure with pulmonary collapse under unilateral ventilation. Definitive evidence whether surgical trauma during thoracotomy is involved in postoperative pulmonary infections has not been clearly demonstrated. The objectives of this study were to evaluate the influence of surgical trauma during thoracotomy on postoperative infections and to investigate the clinical significance of postoperative humoral mediators in pulmonary infections after surgery. We measured serum interleukin-6 (IL-6), IL-8, hepatocyte growth factor (HGF), and nitric oxide (NO) levels in 27 patients undergoing thoracic surgery; the measurements were before and during thoracotomy, 60 minutes after reinflation, and after surgery. The patients were divided into three groups: lobectomy patients (group A), and esophagectomy patients without (group B) or with (group C) postoperative infections. The serum IL-6 and IL-8 levels in group C were markedly elevated 60 minutes after reinflation and were significantly higher than those in group A. The serum IL-8 levels during that period in group C were significantly higher than those in group B. The postoperative serum IL-6, IL-8, HGF, and NO levels were significantly higher in group c than in group B. Taken together, intraoperative hypercytokinemia, especially IL-8, following the thoracic procedure and subsequent reinflation preceded the clinical onset of postoperative infections. Hence postoperative serum IL-6, IL-8, and HGF levels may be useful predictors of infection after esophagectomy.