Purpose : To differentiate the pancreatic adenocarcinoma from focal pancreatitis on CT and ERCP in cases offocal pancreatic enlargement. Materials and methods : We analysed CT findings of 66 patients of pancreaticadenocarcinoma(n=45) or focal pancreatitis(n=21) with respect to size, density, calcification, pancreatic orbiliary duct dilatation, fat plane obliteration around the vessels, direction of retroperitoneal extension,lymphadenopathy, pseudocyst formation and atrophy of pancreas. ERCP available in 48 patients were analysed inrespect to morphologic appearance of CBD and pancreatic duct, and distance between the two ducts. Results : Thepatients in focal pancreatitis were younger with more common history of alcohol drinking. There was no statisticaldifferent in calcifications of the mass (18% in the adenocarcinoma, 33% in the focal pancreatitis), but a tendencyof dense, larger number of calcifications was noted in focal pancreatitis. The finding of fat plane obliterationaround the vessels were more common in pancreatic adenocarcinoma, and fascial thickenings were more prominent infocal pancreatitis, although not statistically significant. On ERCP, there were no differential points of CBD,pancreatic duct morphology, but distance between the two ducts at the lesion center was more wider in focalpancreatitis. Conclusion : Differentiating focal pancreatitis from pancreatic adenocarcinoma is difficult.However, we should consider the possibility of focal pancreatitis in cases of patients with young age, havingalcoholic history in association with CT findings of large numbers of and dense calcifications, and ERCP findingsof prominent separation of two duct at the lesion center.