We investigated the relationship between IL-6 and hemostatic markers regarding surgery in two groups of abdominal surgery: Group I, hepatectomy (20 cases); Group II, gastrectomy (10 cases) and colectomy (10 cases). IL-6 increased during operation and early postoperative period. There is no significant difference between two groups during these periods. But IL-6 increased late postoperatively in 5 patients with complications in Group I. Thrombin-antithrombin III complex (TAT) in both groups increased similarly during operation and continued until early postoperative period. In the fibrinolytic system, tissue plasminogen activator (tPA) and plasminogen activator inhibitor (PAI-1) increased, but not plasmin α 2 plasmin inhibitor cimplex (PIC) in both groups during operation. Significant correlation was noted between the levels of IL-6 and TAT (r=0.482), PAI-1 (r=0.405) in all patients during operation. Following the peak levels of IL-6, Fibrinogen, α 1 antitrypsin and α 2 plasmin inhibitor increased significantly on the 3rd or 5th postoperative day. These increases were prominent and tended to correlate with IL-6 levels in Group II, but not in Group I. In a hepatectomy patient with severe septic complication and disseminated intravascular coagulation, marked increase of IL-6 was seen and suggested a poor prognosis.