During the early phase of our intestinal transplant program, a low-lipid, amino acid-based feeding was employed for most recipients. However, relatively little is known regarding the amino acid absorption by a graft following intestinal transplantation. Sixty Wistar rats were randomly divided into two groups (n = 30). The animals received two-step orthotopic intestine transplantation (OIT), or the control; enterectomy with anastomoses. We measured mucosal Na(+)/K(+)-ATPase and intestinal absorption using stable isotope techniques in vivo. Compared with controls, mucosal Na(+)/K(+)-ATPase activity in OIT decreased by 38.3% and 38.4% at 2 and 4 weeks, and returned to baseline and control group values at 8 weeks. Glycine absorption decreased at 2 weeks and returned to baseline at 4 weeks in OIT compared with that in controls. These results suggested that absorption as assessed by mucosal Na(+)/K(+)-ATPase and glycine, returned to baseline at least 4 weeks after transplantation.