Objective To investigate the dynamical changes of p38MAPK activition in the course of SAP and the relationship between the expression of p38MAPKmRNA and pulmonary injury in rats with SAP. Methods Seventy-two Wistar rats were randomized into three groups: the normal group, normal saline group and SAP group. The SAP group was inflicted with 3.5% sodium tauro-cholate by the method of retrograde pancreatic injection. The animals were sacrificed in 0. 5 h, 6 h, 12 h and 24 h after induction of pancreatitis. Activation of p38MAPK in pulmonary tissues was deter-mined with immunohistochemistry. Intrapulmonary expression of p38MAPK mRNA was detected by RT-PCR. Meanwhile, histological grade of lung injury, wet/dry weight ratio and intrapulmonary con-tent of MPO were detected. Results In the normal group, few p38MAPK activity and expression of its mRNA could be detected, which were markedly increased after induction of pancreatitis. There were intrapulmonary overexpression of p38 MAPK mRNA as compared with elevation of intra-pulmo-nary content of MPO. After the SAP was induced, intrapulmonary expression of p38MAPK mRNA was increased obviously, which peaked at 6h and was still higher than basal activity at 24 h point. In-trapulmonary expression of p38 MAPK mRNA had positive correlation with the histological grade of lung injury and intrapulmonary content of MPO (r=0. 726 and 0. 629, P<0. 01). Conclusion The activation and overexpression of p38 MAPK may be one of the reasons for the lung injury in SAP.