A variety of digestive Enzymes of pancreatic and intestinal origin participate in the breakdown of protein, carbohydrate and lipids. It has been known that some of enzyme output of the intestinal glands can be manipulated by altering components of the diet. The incidence of patients who are suffering from gastrointestinal trouble in Korea is much higher than that of the United States. This fact might correlate with diet composition of Korean and American dishes. These facts are attractive for us to study the effect of diet composition on the digestive enzymes such as amylase, lipase, trypsin and chymotrypsin, and to decide whether the difference of diet composition affects these enzymes and whether such high incidence of gastroin testinal patients in Korea could be adequately explained by change in digestive enzyme activities of the animals fed with different diet. Our previous experiments have shown that pancreatic enzyme activites of rats fed with 5% casein diet which was prepared similarly to Korean diet in terms of protein content only were depressed as much as one fifth of that of control during two weeks feeding period. but it is true that protein is not only depleted but fat is also depleted in Korean dishes. The primary objective of the experiments described herein was to study the effect on the pancreatic enzyme activities of diet which was similarly prepared to Korean dishes and also to study the effect on the pancreatic enzyme activities of varying the proportion of fat to carbohydrate in the diet which is keeping the diet isonitrogenous and isocaloric. Data from this experiment will be discussed ire conjunction with previously published results conducted in our laboratory in order to illustrate how the high incidence of gastrointestinal patients in Korea could be adequately explained by diet prepared in similar composition to the Korean dishes. In a random distribution, male albino rats, weighing the average of 80 gm each were divided into five groups. Group I ; 5% casein : no fat : carbohydrate Group II ; 5% casein : 12% fat : carbohydrate Group III ; 18% casein : no fat : carbohydrate Group IV ; 18% casein : 12% fat : carbohydrate Group V ; 18% casein : high fat : carbohydrate (ratio of fat to carbohydrate 94 : 6) Calorie difference from protein or fat depletion was substitiuted by carbohydrate. At the end of designated time interval, the rats were sacrificed 14-15 hours after the last meal by decapitation. The pancreas was carefully romoved and placed in a cold 0. 25M sucrose solution (4℃). A 5% homogenate in 0.25M sucrose was prepared from the glandular {free of obvious lymph nodes and adipose tissue) portion of the pancreas. 5:% Homogenates were centrifuged (14,000 x g) for 15 minutes to remove cellular debris and whole cells. Enzyme analysis and protein determination were subsequently performed on the supernatant. Protein was determined by Lawry method (1951). Enzyme activity assays were performed using modification of Hepler method (1962) for amylase and the method developed by Cherry and Crandall (1932) for lipase. Chymotryptic assays were performed using a modification of method developed by Rhodes et al. (1957), as a substrate for chymotrypsinogen N-acetyl-L-tyrosine ethyl ester was used. Trypsinogen assay was similarly performed using p-toluene-sulfonyl-L-arginine methyl ester as a substrate. The assays were linear with respect to enzyme concentration over the range used under specified conditions such as temperature (37℃) and incubation period, 30 minutes for amylase, 1 hour for lipase, and for the trypsinogen and chymotrypsinogen the recording of dye disappearing of optical density was recorded 2 to 3 seconds after adding substrate-buffer-indicator The results of the experiments in which the effect of different composition of nutrient which was prepared in similar composition to Korean dishes on pancreatic enzyme acitivities are summarized as the following. When the enzyme activity