Abstract OBJECTIVE: The aim of the study was to compare the recently introduced laboratory markers trypsinogen-2 and trypsin-2-α1antitrypsin complex (trypsin-2-AAT) in serum with lipase and amylase in the diagnostic and prognostic evaluation of patients with acute pancreatitis (AP). METHODS: The analytes were measured on admission in 64 consecutive patients with AP and in 30 controls with acute abdominal disease of extrapancreatic origin. Twenty-one patients had severe and 43 mild AP. As reference methods we used serum amylase and C-reactive protein. RESULTS: In subjects with AP, elevated trypsinogen-2 values (≥90 μg/L) were observed in 63 patients (98%), trypsin-2-AAT values (≥12 μg/L) in 64 patients (100%), lipase values (≥200 U/L) in 64 patients (100%), and amylase values (≥300 IU/L) in 62 patients (97%). The diagnostic accuracy of the markers was evaluated by receiver operating characteristic (ROC) analysis. On admission, trypsinogen-2, trypsin-2-AAT, lipase, and amylase differentiated patients with AP from controls with high accuracy and ROC analyses showed similar areas under the ROC curves (AUC) for trypsinogen-2 (AUC 0.960), trypsin-2-AAT (0.948), lipase (AUC 0.947), and amylase (AUC 0.930). For differentiation between severe and mild AP, trypsin-2-AAT (AUC 0.805) was slightly better than trypsinogen-2 (AUC 0.792), and they were both clearly better than lipase (AUC 0.583), C-reactive protein (AUC 0.519), or amylase (AUC 0.632) ( p < 0.05). CONCLUSIONS: All the markers studied showed high accuracy for differentiating between AP and extrapancreatic diseases. However, trypsinogen-2 and trypsin-2-AAT displayed the best accuracy for predicting a severe AP already at admission, which makes these markers superior for clinical purposes.