Pancreatic necrosis is a well-known risk factor for infectious complications in the patients affected with acute pancreatitis. Dynamic CT with i.v. administration of a large bolus of contrast medium can establish the diagnosis of necrotizing pancreatitis. A series of 49 cases of severe acute pancreatitis was reviewed, and early CT investigations were seen to fail to detect pancreatic necrosis in 22 instances, versus 27 positive cases. In the group of patients with no necrosis, the clinical course was uneventful or characterized by mild complications which regressed spontaneously or by means of adjuvant medical treatment. On the contrary, 17 patients with necrotizing pancreatitis developed severe complications requiring intensive treatment. These complications occurred in 50% of the patients with < 50% of pancreatic necrosis, while the figure rose to 77% whenever more extensive involvement was observed. Our results show that the presence and extent of pancreatic necrosis must be diagnosed as early as possible for prognostic and therapeutic purposes; this can be done by the routinary use of dynamic CT with the administration of large amounts of contrast media at high flow rates.