High mobility group box chromosomal protein-1 (HMGB-1) is a potential late mediator of sepsis and a possible risk factor for postoperative pulmonary complications after esophagectomy. This study aimed to determine the relationship between HMGB-1 and clinicopathological factors and long-term prognosis after esophagectomy for esophageal cancer. We measured perioperative serum HMGB-1 levels using ELISA and HMGB-1 protein by immunohistochemistry expression in resected specimens. Postoperative serum HMGB-1 levels were significantly higher than preoperative levels. Preoperative serum HMGB-1 levels were significantly higher in patients with more intraoperative bleeding, longer intensive care unit stays, and postoperative pneumonia. Postoperative serum HMGB-1 levels were significantly higher in older patients and those with longer operation time and more intraoperative bleeding. There were significant differences in long-term outcomes according to postoperative but not preoperative serum HMGB-1 levels. Multivariate analysis demonstrated that advanced pathological stage, postoperative pulmonary complications, and higher postoperative serum HMGB-1 levels were independently associated with relapse-free survival and overall survival. Preoperative serum HMGB-1 levels were significantly higher in patients with high HMGB-1 expression than those with low HMGB-1 expression by immunohistochemistry, whereas such statistical differences were not observed in postoperative serum HMGB-1. There were no differences in relapse-free survival and overall survival according to HMGB-1 expression by immunohistochemistry. Serum HMGB-1 levels were significantly increased after esophagectomy for esophageal cancer. Elevated postoperative serum HMGB-1, which was associated not only with poor long-term but also short-term outcomes such as postoperative complications, might serve as a potential marker for prognosis in esophageal cancer.