Priming of the gastrointestinal (GI) tract with low-volume feedings before giving full enteral feedings to very premature, high-risk infants is a controversial practice. We designed a study of infants weighing less than 1,250 g and receiving total parenteral nutrition to determine whether GI priming would hasten weight gain, improve tolerance of subsequent feedings, enhance nutritional status, and increase serum concentration of gastrin, a hormone trophic for intestinal growth. Infants were randomly assigned to receive total parenteral nutrition (TPN) alone (N = 21) or GI priming plus TPN (N = 19) for 12 days beginning on day 3 of life. Full-strength premature infant formula was used for priming. Both groups received the same total nutrition. Beginning on day 15, feedings in both groups were increased daily to a maximum of 120 kcal/kg/day on day 20, where they were maintained until day 30. After day 30, the feedings were modified according to the infants' condition. The groups did not differ in birth weight, gestational age, or 5-min Apgar scores. GI-primed infants had improved feeding tolerance after day 20 and a faster rise in serum gastrin during the initial phase of the study. There was no significant difference in weight gain. GI priming improves tolerance of feedings, accelerates rate of rise of serum gastrin during the first weeks of life, and does not increase the risk of feeding complications when compared to TPN alone. This may lead to more rapid maturation of the GI tract in primed infants.