Coagulation studies were performed in patients who underwent abdominal surgery. One hundred and twenty six patients with cholelithiasis, peptic ulcer and gastric cancer were examined. Although fibrinogen increased up to 560 mg/dl postoperatively, DIC did not occur among these patients, at all. For 30 patients who underwent hepatectomy, esophageal transection or pancreatoduodenectomy, HPT, PT, fibrinogen, platelet count, alpha 2-PI, AT-III, plasminogen and DIC score were investigated until 10 postoperative days. As for 13 patients without liver cirrhosis in this group, deterioration of HPT, PT and AT-III was noted on the second postoperative day, however these parameters improved on the fifth postoperative day and all patients recovered uneventfully. On the contrary, as to patients with liver cirrhosis, changes of coagulation parameters were drastic. Significant decrease of HPT, PT, AT-III, plasminogen and increase of FDP and DIC score were noted after operation and these values deteriorated with time in certain cases. Seven patients out of 17 died of DIC and multiple organ failure. More than half of these patients received Gabexate Mesilate (GM) injection in a dose of 1200 mg/day postoperatively for more than 5 days to prevent DIC. In patients who underwent hepatectomy due to hepatocellular carcinoma with liver cirrhosis, the increase of FDP and DIC score seemed to be inhibited by GM on the fifth postoperative day.