An inflammatory mass in the head of the pancreas is reported in 18-50% of patients with chronic pancreatitis. When the clinical history is misleading, differential diagnosis between chronic pancreatitis and pancreatic cancer may be very difficult. Pancreaticoduodenectomy is considered the treatment of choice, if cancer is still suspected despite negative biopsy. From January 1987 to December 1992 we performed 42 pancreaticoduodenectomies, 36 for malignancies of the pancreaticoduodenal area and 6 for chronic pancreatitis suspected to have a pancreatic cancer. In three additional cases of chronic pancreatitis, we performed a pancreaticoduodenojejunal anastomosis after complete opening of the pancreatic duct and excision of the papilla of Vater. Frozen section and definitive histological examination of the pancreas and ampulla excluded malignance in all three patients. They are alive and well 60, 36, and 20 months after operation. With this procedure, frozen-section examination of the distal part of the pancreatic and biliary duct, the papilla, and the periductal pancreatic tissue can be performed, while this is impossible with the usual pancreaticojejunostomy. We can therefore reasonably exclude a small cancer of the periampullary area and perform a wider derivative procedure, instead of a pancreaticoduodenectomy, in patients with an inflammatory mass of the head of the pancreas.