Edematous pancreatitis was induced in 12 male Sprague-Dawley rats using supramaximal doses of the cholecystokinin analogue cerulein (5 micrograms/kg per hour). The microvasculature of the pancreas, liver, and kidney was examined using scanning electron microscopy of microvascular corrosion casts in 12 test animals and four controls at intervals of 30 minutes, 1 hour, 2 hours, and 4 hours. Distortion of the pancreatic and hepatic microvasculature was seen as early as 30 minutes and progressed during the study period. The renal vasculature remained normal throughout. Light microscopic analysis revealed no morphologic abnormalities in the walls of the pancreatic, hepatic, or renal microvasculature. This study demonstrates that cerulein-induced pancreatitis is associated with marked distortion of the pancreatic and hepatic microvasculature; the abnormalities start early in the disease and progress during the study period.