The present study was undertaken to determine whether a restricted diet could affect the exocrine pancreatic function in rat pancreas. Male Sprague-Dawley rats of 5 weeks of age were fed either unrestricted or restricted amount of diet for an 8 weeks, experimental period. The restricted groups received 60, 80 or 90% of the diet taken by the unrestricted group. The animals of restricted groups showed a significantly low growth rate as compared with the unrestricted anima1s. The weights of the kidney, 1iver and heart were lower in the restricted rats than those in the unrestricted rats. Although the weight of the pancreas in the restricted groups was less, the activities of amylase (EC-3. 2. 1. 1), trypsin (EC-3. 4. 21. 4) and chymotrypsin (EC-3. 4. 21. 1) were not reduced. These activities per mg pan, creatic tissue were significantly higher than that of the Unrestricted rats. Except for juice flow, there sponses induced by a secretagogue, caerulein, in the restricted rats were significantly higher than that in the unrestricted rats. From the results, it was concluded that a restricted diet could potentiate the exocrine pancreatic function. However the food efficiency ratio was significantly lower in the restricted than that in the unrestricted rats. This discrepancy could perhaps be explained by the increased motor activity observed in the restricted groups.