Pancreatic abscess has become the most common cause of death from acute pancreatitis. Since computed tomography (CT) permits noninvasive imaging of the peripancreatic anatomy, the relationship of early CT findings to late pancreatic sepsis has been evaluated in 83 patients with acute pancreatitis. Pancreatic abscesses developed in 18 patients and were responsible for five of the six deaths in this study. Initial CT findings were graded: A = normal, in 12 patients; B = pancreatic enlargement alone, in 19; C = inflammation confined to pancreas and peripancreatic fat, in 17; D = one peripancreatic fluid collection, in 12; and E = two or more fluid collections, in 23. The incidence of pancreatic abscess in grades A and B was 0%; in grade C, 11.8%; in grade D, 16.7; and in grade E, 60.9%. The severity of pancreatitis was also graded by previously reported prognostic signs as "mild" (0-2 signs) in 56 patients, "moderate" (3-5 signs) in 22, and "severe" (greater than or equal to 6 signs) in five patients. The incidence of abscesses in mild disease was 12.5%; in moderate, 31.8%; and in severe, 80%. Fluid collections on CT resolved spontaneously in 19 of 35 (54.3%) patients. Abscess developed in two patients with no fluid collections on initial CT study. No abscess occurred in 31 patients with CT grades A or B, and in one of 22 patients (4.5%) with CT grade C or D and less than three positive prognostic signs. Among 30 patients with CT grade E or CT grade C or D and three or more positive prognostic signs, 17 (56.7%) developed abscesses. All deaths were in patients with five or more positive prognostic signs. Early imaging of the pancreas by CT identifies a group of patients with increased risk of pancreatic abscess. Identification of this group is improved further by use of early objective prognostic signs.