['The prediction of the course of acute pancreatitis and its arising complications is of clinical importance. The aim of this study was to judge the time course and relevance of matrix metalloproteinase-9 (MMP-9), a PMN-derived protease, for the development of pulmonary complications in two models of acute pancreatitis.', 'MMP-9 was evaluated in a standardized experimental model of acute pancreatitis. Mild edematous (n = 12) and severe necrotizing pancreatitis (n = 48) were induced by intravenous cerulein or intravenous cerulein and intraductal application of glycodeoxycholic acid and compared to control animals. 1, 6, 9, 12, 24 and 72 h after induction, rats were sacrificed and damage to the lung and the pancreas was quantified by histology and extravasation of Evans blue. At 1, 6, 9, 12, 24 and 72 h, we determined MMP-9 in serum by ELISA.', 'In our model, MMP-9 in serum was increased in the group with severe acute pancreatitis in comparison to mild edematous pancreatitis and controls at each evaluated time point (p < 0.05). The maximum release of MMP-9 preceded the development of pulmonary complications, verified by histology and extravasation of Evans blue. MMP-9 showed a negative predictive value of 96.2% and a positive predictive value of 100% for the development of pulmonary complications.'] Does mMP-9 in serum correlate with the development of pulmonary complications in experimental acute pancreatitis?