Nutritional function following autografting of the entire small bowel was followed in 11 dogs for 12 months. Although positive nitrogen balance was recovered within a few weeks, the animals did not achieve their preoperative body weight for up to 6 months. Fat and D-xylose absorption remained depressed and never fully recovered. Hematocrit and serum iron did not normalize until the second postoperative month or later. Abnormal serum albumin and albumin/globulin ratio persisted for 12 months. When the mesenteric vein was anastomosed to the vena cava rather than to the portal vein, this group had more severe abnormalities in body weight, hematocrit, total protein, and serum albumin, in addition to a significant rise in liver enzymes. These findings represent a discouraging portent for the functional utility of small bowel transplants.