In this study we determined the clinical accuracy of α 2 - macroglobulin, α-amylase, C-reactive protein, lipase, non-esterified fatty acids, pancreatic α-amylase and phospholipase A in the diagnosis and prognosis of acute pancreatitis in a group of patients with acute abdominal pain using receiver operator characteristic curve analysis. We investigated 59 patients with acute pancreatitis and 72 patients with extrapancreatic diseases of gastrointestinal origin. On the basis of initial enzyme activities, at cut-offs of 245 U/l for amylase, 656 U/l for lipase, and 182 U/l for pancreatic α-amylase, the diagnostic efficiencies were 0.993, 0.980, and 0.975, respectively. Receiver operator characteristic curve analysis showed the same diagnostic accuracies. We evaluated the accuracy of serum α 2 -macroglobulin, C-reactive protein, non-esterified fatty acids and phospholipase A for differentiation between acute necrotizing pancreatitis and acute oedematous pancreatitis. C-reactive protein had the highest prognostic accuracy of the parameters studied (the area under curve = 0.9082) and at a cut-off value of 126 mg/l, sensitivity and specificity were 0.759 and 0.912, respectively. The role of the clinical laboratory in the investigation of patients with acute pancreatitis continues to evolve and biochemical parameters are a good diagnostic and prognostic option.