In order to evalute the diagnostic value of ascitic fluid cholesterol, CEA and CA 19-9 analysis in differentiation between malignant from cirrhotic ascites, the. authors studied 37 cases of malignant ascites patients and 42 cases of cirrhotic ascites patients and analyzed the levels of the cholesterol, CEA and CA 19-9 of those cases from April, 1989 to October, 1990 in Seoul Adventist Hospital. The results were as follows; 1) The median and mean values of cholesterol and CEA were significantly higher in malignant ascites compared to cirrhotic ascites(p<0.01). 2) There was no significant difference in CA 19-9 levels betsveen cirrhotic ascites and malignant ascites. 3) The discrimination value for cholesterol was 45 mg/dl. We defined the upper limit of normal value for CEA and CA 19-9 as 5 ng/ml and 37 U/ml, respectively. 4) The diagnostic efficiency was 89% for cholesterol, 90% for CEA and 81%. for CA 19-9. 5) There was a significant positive correlation between cholesterol and CA 19-9 (r=0.41, p<0.01), CEA and CA 19-9 (r=0.67, p<0.01), respectively. It was concluded that the measurement of ascitic fluid cholesterol and CEA levels is useful in differential diagnosis between malignant from cirrhotic ascites.