The effect of repeated oral administration of polydextrose and pectin on intestinal macromolecular transport and digestive enzymes development was examined in the suckling rat. The administration of polydextrose for 7 days resulted in pancreatic hyperplasia, followed by the enhancement of trypsin activity. The length of the small intestine and the wet weight of the cecum were significantly increased by polydextrose treatment. Maltase activity was increased in a dose dependent manner by polydextrose, but not by pectin treatment. Lactase activity was not changed by either treatment. The absorption of bovine IgG was precociously depressed by polydextrose, but not by pectin treatment. These results suggest that oral administration of polydextrose induces precocious maturation of the small intestine and exocrine pancreas in the suckling rat.