The use of "elemental" diets has received widespread acceptance in the treatment of chronic protracted diarrhea of infancy1,2 and other gastrointestinal disorders.3,4 Two frequently used commercial "elemental" formulations are Vivonex (Norwich- Eaton Pharmaceuticals, Norwich, NY) and Pregestimil (Mead Johnson and Co, Evansville, IN), both of which utilize glucose polymers as the major source of carbohydrate. Prior to the fall of 1978, Pregestimil contained simple glucose, instead of polymers, but was changed in order to decrease the formula osmolality. We report an infant recovering from chronic protracted diarrhea who was unable to tolerate glucose polymers, but thrived on the "old" glucose-containing Pregestimil formulation.