Thirty-five patients with acute pancreatitis underwent serum monitoring of alpha-1-protease inhibitor, alpha-2-macroglobulin, complement factors C3 + C4, and C-reactive protein (CRP). Edematous interstitial pancreatitis was shown to be present in 13 patients by contrast-enhanced computed tomography (CT) and laparotomy (n = 3). Necrotizing pancreatitis was confirmed by laparotomy (n = 21) and contrast-enhanced CT. There were significant differences between the serum values of all measured parameters in the two morphologically defined pancreatitis groups. The best discriminating factors were CRP and alpha-2-macroglobulin, showing 95% and 85% overall detection rates for pancreatic necrosis, respectively.