Fetal tissue transplantation has gathered considerable interest among researchers dealing with organ transplantation. A large number of studies concerning fetal intestinal transplantation have been published in the past 2 decades, almost all of them aiming to determine the feasibility of a properly functioning fetal transplant in continuity with the host's own enteral system. This study was designed to determine the absorptive capacity of the neogut in vivo, without anastomosing the transplant to the host's intestine, and to evaluate its use as an accessory enteral segment. Intestinal segments taken from Wistar albino fetuses were transplanted subcutaneously into the abdominal wall of 20 Sprague-Dawley rats. Immunosuppression was maintained by daily cyclosporin A (Cy A) 10 mg/kg injections s.c. and evaluated by determination of serum Cy A level and T-helper/T-suppressor cell ratio. The neogut was converted into a Thiry-Vella loop 2 weeks after transplantation. A test solution composed of 20% glucose and Trophamine was perfused via the stomas; glucose and amino acid absorption gradients were calculated. The gamma-glutamyl transferase (GGT) activity and mitotic index of the neogut were determined. Results were compared to those obtained from the host. There was no significant difference (P > 0.05) in glucose absorption between the neogut and the host tissue. Amino acid absorption and specific GGT activity were significantly less (P < 0.01) in the neogut. There was no significant difference (P > 0.05) between neogut and host intestine in mitotic index. Our data support the idea of using a transplanted fetal intestinal segment as an accessory feeding route.