Total parenteral nutrition (TPN) is accepted important therapeutic adjunct in spite of many complications for management of pediatric patients who aren't allowed to eat. Recently, bacterial translocation was added to the complications of TPN. The purpose of this study was to examine the influence of TPN on the gut in immature rats. 65g rats were randomized to one of four groups: Group C (control) received food and water ad libitum. Group P (TPN) received standard TPN solution. Group G (TPN+GLT) received glutamine (7g/400ml of TPN). Group E (TPN with enhanced protein) received TPN solution with enhanced protein (18.5g/400ml), without GLT. CFU of E. coli in mesenteric lymphnodes was significantly higher in group P than in other 3 groups at 5 days. Hepatic glutathione was significantly higher in group G than in group P and group E at 7 days. Weight of wet intestine was the highest in group C in all groups, and significantly higher in group G than in group P and group E at 3 and 7 days. Mucosal protein of group C was the highest of those of 4 groups. That of group G was significantly higher than those of group P and G in 5 and 7 days. Mucosal thickness and villous height were the highest in group C in 4 groups. Mucosal thickness was significantly higher in group G than in group P and group E at 5 and 7 days. Villous height was significantly higher in group G P and group E at all days. These results suggest that TPN promotes intestinal atrophy from early days after TPN in immature rats, that glutamine might play a role in maintenance of structural integrity of intestine, and that glutamine would prevent the bacterial translocation.