"Groove pancreatitis" is a form of segmental pancreatitis affecting the head of the pancreas which is localized within the "groove" between the head of the organ, the duodenum and the common bile duct. We diagnosed this form of pancreatitis in 30 out of 123 surgical duodenopancreatectomy specimens of chronic pancreatitis (24.4%). In a comparison with non-segmental chronic pancreatitis, no differences was observed in age and sex distribution or in alcohol consumption. Clinically, in contrast, preceding diseases of the biliary system, peptic ulcers and gastric resections were more frequently indicated. The cardinal clinical finding is frequently duodenal stenosis; in sonographic and CT examinations, the cicatricial "plate" in the "groove" represents as a "tumor", so that--also on account of the frequent duodenal stenosis--a carcinoma of the head of the pancreas may be suspected. In groove pancreatitis, the pancreatic duct system is grossly normal, calcifications or intraductal protein plugs being rare and an adaptive intimal fibrosis of the intrapancreatic arteries and arterioles is found only within the cicatricial area. Very commonly, scarring of the duodenal wall, stenosis of the duodenum, true duodenal wall and pancreatic cysts are detected. Aetiopathogenetic possibilities are previous diseases of the biliary system, peptic ulcers, gastric resections, true duodenal wall cysts, pancreatic head cysts, pancreatitis in duodenal pancreatic heterotopia, and disturbances of pancreatic juice outflow in Santorini's duct in the absence of the minor papilla, and hyperstimulation in consequence of chronic alcoholism.