Acute pancreatitis was initiated in the isolated ex vivo, perfused canine pancreas preparation by exposing the gland to a 2 hour period of ischemia before a 4 hour perfusion period. The pancreatitis was manifested by edema formation, weight gain, and hyperamylasemia. When the osmotically active agent albumin was added to the perfusate at the end of the ischemic period, virtually no edema developed, weight gain was minimal, and the amylase level remained within normal limits during the subsequent 4 hour perfusion period. This suggests that a change in capillary permeability may be an early step in the pathogenesis of ischemia-induced pancreatitis in this experimental model.