Twelve pancreases from human infants one year old or less were analyzed for tissue insulin and amylase content before and after dispersal of pancreatic fragments by mincing collagenase digestion. Tissue insulin and amylase content provide an index of pancreatic islet mass and exocrine digestive enzyme content, respectively. The results were compared with similar analyses performed on juvenile and adult human pancreases before and afterislet isolation and on intact and dispersed neonatal rat and adult rat pancreases. Infant human pancreas has an average tissue insulin concentration of 1,128 μg/gm of tissue and a total insulin content of 1,718 μg/pancreas, as against values of 140 μg/gm of tissue and 7,209 μg/pancreas for adult human pancreas. Average tissue amylase concentration is 0.24 mg/gm of tissue in infant human pancreas and 3.0 mg/gm of tissue in adult human pancreas. The insulin/amylase ratio in infant pancreas is 4,800, as against 46 in the adult pancreas. Neonatal rat pancreas, which can be dissociated and transplanted without separation of islet and exocrine components, has a similarly high tissue insulin and low tissue amylase content when compared with adult rat pancreases. Infant human pancreas has a total islet mass 24% that of an adult human pancreas, and neonatal rat pancreas has a total islet mass 11% of that of an adult rat pancreas. One neonatal rat pancreas prepared by minimal collagenase digestion can cure diabetes when transplanted via the portal vein to a rat. Following dispersal of infant human pancreas by collagenase digestion, the islet content and the insulin/amylase ratio of the recovered tissue equals or exceeds that which usually can be isolated from adult cadaver pancreases. Infant human pancreas is a rich source of islet tissue that is relatively uncontaminated by exocrine digestive enzymes. After dispersal, infant human pancreas may be ideal for transplantation to selected diabetic patients.