Extrapancreatic findings at computed tomography (CT), performed within 24 h in 42 consecutive episodes of acute pancreatitis, were classified according to a scoring system (EP score) and were correlated to Ranson's prognostic signs, to duration of hospital stay, biochemical changes in plasma and pancreatic ischaemia found at CT with contrast enhancement. Increasing EP score was found to be related to increasing number of positive Ranson's signs, longer hospital stay and pancreatic ischaemia. Plasma levels of immunoreactive cationic trypsin and amylase were not proportional to EP score. alpha 1-protease inhibitor, antichymotrypsin but not immunoreactive pancreatic secretory trypsin inhibitor increased proportionally to EP score. No changes related to EP score were seen in alpha 2-macroglobulin levels. Serum levels of trypsin-alpha 1-protease inhibitor complex were maximal after 3 days and most pronounced in cases with high EP scores. Plasma levels of factor X, alpha 2-antiplasmin and C1-esterase inhibitor were found to be inversely proportional to EP score.