ObjectiveTo evaluate the effect of polymorphonuclear neutrophils (PMN) on liver damage in acute pancreatitis. MethodsSeventytwo wistar rats were randomly divided into acute pancreatitis (AP) group, acute pancreatitis with PMN depleted (APD) group and sham operation (SO) group. Liver damage was assessed by histological changes and the level of alanine aminotransferase (ALT) in serum. The number of PMN infiltration in liver was reflected by myeloperoxidase (MPO). ResultsMPO significantly increased from 6 to 24 hours in AP and APD groups. However, the level of MPO was significantly higher in AP group than that in APD group. ALT significantly increased from 3 to 24 hours in these two groups, but the level of ALT was significantly lower in APD group than that in AP group. Meanwhile, the hepatic pathological changes were more severe in AP group than that in APD group. ConclusionPMN play an important role in liver damage during acute pancreatitis.