Elemental or chemically defined diets are used in a variety of gastrointestinal disorders to sustain enteral nutrition, avoid the potential danger of central venous hyperalimentation and reduce intestinal and pancreatic secretions. The two diets available commercially are used interchangeably despite important differences in composition. The present study compared pancreatic exocrine secretory responses to these two diets in dogs. Infusion of high- and low-fat elemental diets resulted in less enzymatic output than a standard blenderized diet. Pancreatic volume and bicarbonate content were similar with the low-fat elemental diet and the blenderized diet, but volume was increased by 30% and bicarbonate increased nearly twofold during infusion of the high-fat elemental diet. The results support the hypothesis that a low-fat elemental diet is preferable for intragastric feeding when the therapeutic goal is to minimize pancreatic secretion.