OBJECTIVE : High mobility group box 1 (HMGB1) is produced by inflammation. Regarding liver injuries, HMGB1 is reportedly involved in liver regeneration. The present study investigated the use of HMGB1 as a postoperative marker of surgical course in patients with liver cancer. METHODS : Patients were enrolled if they had liver cancer, had undergone liver surgery, and did not develop postsurgical complications. Patients who received emergency surgery or patients with unresectable cancerous lesions were excluded. Blood samples were preoperatively obtained as well as at 1 day, 1 week, and 4 weeks following surgery; white blood cell count, serum C-reactive protein, serum albumin, and serum HMGB1 levels were measured. RESULTS : A total of 36 patients were included in this study. HMGB1 levels significantly changed over time, increasing from a median of 7.1 ng/ml (preoperatively) to 13.9 ng/ml at 1 week postoperatively, and then decreased to 6.3 ng/ml at 4 weeks postoperatively. Peak HMGB1 levels were delayed, and elevated HMGB1 levels persisted as compared with the changes in conventional markers. CONCLUSIONS : HMGB1 indicates a unique perioperative inflammatory state in patients with liver cancer. Serum HMGB1 may serve as a marker for monitoring surgical course in patients undergoing surgery for liver cancer.