A variety of digestive enzymes of pancreatic and intestinal origin participate in the break down 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 suffering from gastrointestinal trouble in Korea is much higher than that of United States. This fact might correlate with diet composition between Korean dishes and American dishes. These facts attractive for us to study the effect of diet composition on the digestive enzymes such as amylase, lipase, trypsin and chymotryosin, whether the difference of diet composition is effect on these enzymes and whether such high incidence of gastrointestinal patient in Korea. could be adequately explained by change in digestive enzyme activities of the animals fed with different diet. In a random distribution, male albino rats, weighing the average of 85 gm each were divided into three groups. The groups were designated as group I (5% casein diet), group II (18% casein diet), group III (25% casein diet). The rats were trained to eat each designated diet during 1 hr period every 12 hrs. For two weeks (28 feedings) the food intake of all rats was ad libitum. At the end of the 28 th feeding, and 2.5 hours after the beginning of the 1 hr feeding period, rats were Stilled by decapitation. The pancreas was carefully removed and placed in a cold 0.25 M sucrose solution (4 ) . A 10% homogenate in 0.25M .sucrose was prepared froth the glandular (free of obvious lymph nodes and adipose tissue) portion of the pancrens. The 10% homogenate was assayed for protein and enzyme activity. Protein was determined by micro -=Kjeldah1 method. Amylase activity assays were performed using a modification of Somogi`s method. Lipase activity assays were performed using a modification of the method developed by Cherry and Crandall. We found that the standard curve of amylase and lipase were proportional to the enzyme concentration under specified conditions such as temperature, (37°) and incubation period, 30 minutes for amylase, 1 hr for lipase. Results of the experiments in which the effect of protein content on pancreas tissue enzyme activity are summarized as following. When the enzyme activity in the pancreas, expressed as %, in the corresponding tissue fed with 18% casein diet, enzyme activity of amylase and lipase were depressed by 12.5% and to 29.6% during the 28 feeding of the 5% casein diet, Some of animal in group I receiving 28 feedings were transferred to the 18% and 25% casein diet, then pancreatic tissue enzymes were assayed 2. 5 hr after the initiation of the 1 hr feeding period, on the 2nd day (4th feeding) 5th day (10th feeding) and 7th day (14th feeding) , The recovery of amylase and lipase activity were remarkable. This recovery was not seen until fourth feeding. It was remarkably rapid a#ter the fourth feeding to tenth feeding` From the tenth to the fourteenth feeding the enzyme activity slowly recovered to 80% activity for the 18% casein diet, No significant difference in the recovery rate of enzyme was observed between 18% casein diet, 25% casein diet, and 5% casein diet in the rats shifted to group II and group III diets. On the other hand, immediately after the first feeding there was recovery of Iipase enzyme activity, to about normal by the tenth feeding of the 25% caesin diet. However, the recovery of pancreatic lipase enzyme activity of rats 18% casein digit was not as rapid as on the 25% casein diet. These results suggest that there are remarkabls effects of diet on digestive amylase and lipase enzyme activities. This may be due to the decreased amout of amino acid in the dietary protein. It can be postulated that the decrease in dietary protein affects synthesis and secretion of pancreatic amylase and lipase, and then with the intracellular structure of the cell, resulting tissue debility. The effect of diet on trypsin and chymotrypsin activ