In view of the presence of prostaglandins in milk, studies were performed to determine if maturational differences are present in the gastrointestinal processing of exogenous prostaglandin F2 alpha. Suckling (10- to 14-day-old) and weanling (30-day-old) rats were gastrically fed 3H-labeled prostaglandin F2 alpha and killed 2 h later. Characterization of radioactivity present in the stomach from animals of both age groups revealed low prostaglandin F2 alpha metabolism. Analyses of proximal, middle, and distal intestinal segments revealed age-related differences in prostaglandin metabolism. The amount of unmetabolized PGF2 alpha in intestinal segments of suckling rats ranged from 11.4 to 13.5%. In weanling rats, there was a tendency toward increased amounts of intact PGF2 alpha in proximal (16.3 +/- 1.6%) and middle (17.6 +/- 2.2%) regions; however, 25.9 +/- 1.9% of the tissue radioactivity present in the distal small intestine of weanling rats was authentic PGF2 alpha, significantly greater than that of the distal segment of suckling rats. The intestine of weanling rats contained greater amounts of less polar metabolites. These results indicate that orogastrically fed prostaglandin can pass through the gastrointestinal tract of developing rats and be delivered to the distal intestinal mucosa intact.