Cyclosporine prolonged the survival of ectopic small bowel allografts in a canine model. A 9-fold increase in mean survival as compared with controls was obtained. Addition of prednisone to cyclosporine did not result in further graft prolongation, but improved the gross and histological appearance of the allograft. Monitoring the motility and histology of the allograft appears to be useful in predicting approaching rejection. Xylose absorption was not helpful in this regard. A new technique for measuring fat absorption in the transplant is described. Following allografting, fat absorption is resumed by 14 days posttransplantation.