The present study was aimed at evaluating the role of the Autonomic Nervous System (ANS) in the insulin (IRI) response to arginine in humans. Nine patients who were recipients of simultaneous segmental pancreatic and renal grafts (6 receiving steroids and azathioprine as immuno suppression therapy, 3 treated with Cyclosporine A), 3 non-diabetic patients with kidney grafts (receiving steroid and azathioprine) and 10 normal subjects were studied. Arginine induced a clear IRI release in all subjects with no significant difference among the groups. Somatostatin (SRIF) inhibited IRI release to a similar degree in all subjects. Since the transplanted pancreas is completely denervated, these data suggest that the integrity of the ANS is not essential to the IRI response to arginine, nor for the inhibitory effect of SRIF on IRI release.