In 24 dogs a 100 cm length of terminal ileum was autografted as an orthotopically vascularized Thiry-Vella segment. In six dogs absorption, motility and histology were studied in detail and in two intestinal myo-electrical activity was recorded. At a second operation 5 weeks after autotransplantation the Thiry-Vella segment was returned to its normal anatomical position in the intestinal stream and 2 months later all the non-transplanted intestine was resected. Eighteen grafts were technically successful. Intestinal myo-electrical activity was normal by the second day after transplantation while intestinal transit and contractile activity recovered within 10 days. Mucosal morphology and intestinal absorption had largely recovered by 10 days after grafting but absorption of oleic acid was impaired for 4 weeks. Ten dogs with severe short, bowel syndrome but intact ileocaecal valve were maintained in good health for more than 7 months by a 100 cm ileal autograft.