BACKGROUND/AIMS: Obstruction of the main pancreatic duct leads to progressive obstructive and atrophying pancreatitis in the cat. The question remains whether "early" derivative procedures can halt the destructive process or not? METHODOLOGY: Twelve cats submitted to total obstruction of the main pancreatic duct developed chronic obstructive pancreatitis as documented by histopathology. After 5 weeks, five animals underwent a caudal pancreaticojejunostomy, the others served as controls. Pancreatic histopathology and ductography was conducted in both groups, as well as tests of endocrine and exocrine functioning. RESULTS: Three of the five cats that underwent a derivation operation died 3-5 weeks following the second operation mainly due to infection, but 2 cats could be followed-up for up to 52 weeks. The histological signs of inflammation and early fibrosis gradually disappeared and the pancreas returned to normal as assessed by histology, radiology and pancreatic function tests. In contrast, cats not submitted to the derivation procedure developed an atrophic chronic pancreatitis. CONCLUSIONS: A desobstructive operation, carried out 5 weeks after total obstruction of the main pancreatic duct in cats, can halt the progression of chronic obstructive pancreatitis and leads to restitution of the pancreas as assessed by histology, radiology and function tests.