OBJECTIVE We have evaluated a new urinary trypsinogen-2 test strip, based on the principle of immunochromatography, in the diagnosis of acute pancreatitis induced by endoscopic retrograde cholangiopancreatography (ERCP). METHODS One hundred six consecutive patients undergoing ERCP (with opacification of the pancreatic duct) at the Helsinki University Central Hospital were included in the study. Patients were tested with a urinary trypsinogen-2 test strip six hours after ERCP. Quantitative trypsinogen-2 as well as serum and urine amylase values were measured before the procedure and six hours after it. RESULTS In patients developing pancreatitis after ERCP, the median urinary trypsinogen-2 concentration six hours after the endoscopic procedure was 1780 micrograms/l (range 29-10,700 micrograms/l), and in patients without pancreatitis the median concentration was 3.6 micrograms/l (range 0.1-3390 micrograms/l; P < 0.0001). The sensitivity and specificity figures for the urinary trypsinogen-2 test strip results in diagnosing post-ERCP pancreatitis were comparable (81% and 97%, respectively) to those for serum amylase (91% and 96%) and urine amylase measurements (81% and 95%). The test strip showed a good correlation (kappa = 0.75) with the quantitative trypsinogen-2 assay. CONCLUSIONS The increase in urinary trypsinogen-2 concentration after ERCP reflects pancreatic injury, and can be detected by the test strip. Patients should be tested before the ERCP procedure as well, since elevated baseline values occur. The test is reliable and easy to perform even on an outpatient basis. However, its clinical usefulness requires evaluation in further trials.