There are no systems for the rapid diagnosis and prognosis of acute pancreatitis in the Emergency Department. Our aim was to evaluate whether the combined use of serum lipase and interleukin-6 or serum lipase and C-reactive protein is able to simultaneously establish both the diagnosis and the prognosis of acute pancreatitis. Eighty patients with acute abdomen were studied on admission to the Emergency Room. Forty patients had nonpancreatic acute abdomen, and 40 had acute pancreatitis (25 had mild acute pancreatitis and 15 had severe pancreatitis). Forty healthy subjects comparable for sex and age were also studied as controls. Lipase, interleukin-6, and C-reactive protein were determined on serum in all subjects. Using lipase to discriminate between patients with nonpancreatic acute abdomen and patients with acute pancreatitis (cutoff values ranging from 419 to 520 U/L), one patient with acute pancreatitis was not identified correctly. To discriminate between patients with severe acute pancreatitis and those with mild pancreatitis in the remaining 39 patients, interleukin-6 (cutoff value, <3.7 microgram/L) had a sensitivity of 100% (15 of 15) and a specificity of 83% (20 of 24); 75 of 80 (94%) patients were classified correctly. C-reactive protein (cutoff values ranging from 6 to 7 mg/L) showed a lower prognostic efficiency than interleukin-6: sensitivity of 87% (13 of 15) and specificity of 46% (11 of 24). Sixty-four of 80 patients (80%) were classified correctly. The area under the ROC curve for interleukin-6 (0.911 +/- 0.049) was significantly (P = 0.013) greater than that for C-reactive protein (0.685 +/- 0.090). The combined use of serum lipase and interleukin-6 is useful in simultaneously establishing both the diagnosis and the prognosis of acute pancreatitis.