The diagnostic and therapeutic approach to Acute Pancreatitis (A.P.) is directly related to the clinical presentation. The Authors reviewed the data of 66 patients, hospitalized between October 1989 and December 1991, to verify the effectiveness of the prognostic criteria suggested by Ranson (1974), Mercadier (1977) and Imrie (1978). A.P. was of biliary origin in the majority of the patients (63.5%); five patients (7.5%) had an acute alcoholic pancreatitis, while the aetiology was traumatic or unknown in the remaining cases. A complicated clinical course was defined by the development of pseudocyst, pancreatic abscess, digestive haemorrhage, death or prolonged hospitalization (more than 20 days). The 28.8% of the patients developed complications during hospitalization. There were seven pancreatic pseudocysts, six pulmonary complications, three renal insufficiencies, two vascular complications, two sepsies and a gastrointestinal haemorrhage. The mean hospitalization period was 15.1 days (range 1-112). The Authors conclude that the three different prognostic criteria are equally useful to test the severity of A.P. attacks allowing to identify patients with the higher risk to develop complications during hospitalization.