Early assessment of severity in acute pancreatitis (AP) has a major impact on further treatment. Previous studies have shown that human pancreas-specific protein (hPASP)/procarboxypeptidase B (PCPB) is a new diagnostic and prognostic marker in AP. In the present study we focused on the prognostic properties of this parameter and analyzed the clinical value of hPASP in discriminating edematous from necrotizing AP. The results were compared to those for C-reactive protein (CRP) and lactate dehydrogenase (LDH). A total of 70 patients was enrolled in this prospective study. Based on contrast-enhanced computed tomography or intraoperative results, 39 patients (27 male, 12 female; median age, 42 years; median Ranson score, 6) suffered from necrotizing pancreatitis (NP) and 31 patients (12 male, 19 female; median age, 57; median Ranson score, 1.5) from acute interstitial-edematous pancreatitis (AIP). Serum concentrations of hPASP/PCPB, CRP, and LDH were measured at 24-h intervals over 14 days after admission by a radioimmunoassay (upper normal value, 60 ng/ ml), a lasernephelometric assay (upper normal value, 4 mg/L), and an enzymekinetic method (upper normal value, 240 U/L), respectively. During the overall observation period concentrations of hPASP/PCPB, CRP, and LDH were significantly higher in patients with NP compared to those with AIP. Based on receiver operating characteristics, the best cutoff levels for predicting NP were >200 ng/ml for hPASP/PCPB, >140 mg/L for CRP, and >290 U/L for LDH. Discrimination between AIP and NP was best on day 3 for both hPASP/PCPB (sensitivity, 91%; specificity, 64%; accuracy, 79%) and CRP (sensitivity, 83%; specificity, 84%; accuracy, 83%) and on day 5 of AP for LDH (sensitivity, 88%; specificity, 100%; accuracy, 91%). The overall accuracy in differentiating AIP from NP within the first 4 days after onset of symptoms was 74% for hPASP/PCPB, 75% for CRP, and 76% for LDH. None of the parameters correlated with the extent of necrosis or the etiology of AP. hPASP/PCPB provides good discrimination between AIP and NP at an early stage of the disease, with results comparable to those for CRP and LDH. Although hPASP/PCPB is both disease specific and predictive for necrosis, the clinical use of this test in its present form is limited due to drawbacks in terms of test performance and cost factors.