68 disease free patients were investigated prospectively after jejunal gastric replacement [jejunal interposition (JI): n=40; Roux en Y reconstruction (RY): n=28]. Used function tests were: scintigraphic emptying studies, hydrogene breath test, hepatobiliary sequential scintigraphy, oral glucose tolerance test, and upper intestinal manometry with 5 measuring ports (times of investigation: 6.-12. week and >1 year postoperatively). Patients with JI showed a better weight gain (p=0,001), a lower reflux rate (p=0,01), a slower orocecal transit time (p=0,05), a prompter bile flow after meal stimulation (p=0,02), and lower peak glucose levels (p=0,001). The emptying patterns of the different gastric substitutes were not different. A higher incidence of retrograde contractions in RY and a electromechanical coordination between duodenum and gastric substitute in JI were detected, We conclude that the postoperative function of the jejunal gastric substitute does not depend on it's emptying pattern or volume but on the motility patterns of the entire intestinal tract which seem to be strongly influenced by the choice of the jejunal reconstruction.