Objective：To investigate the expression of nuclear factor-κB(NF-κB),matrix metalloproteinase-2(MMP-2),tissue inhibitor of metalloproteinase-2(TIMP-2) in the kidneys of rats with acute renal trauma,and to discuss the influence of ulinastatin on their expression and its protective mechanism on the kidney.Methods: The animal model was established by striking the rachi-costaz zone with falling object from the height of 45 cm.Sixty-six rats were randomly divided into three groups:normal control group (C,n=6),trauma group (TRA,n=30),and ulinastatin+trauma (UTI,n=30); the last 2 groups were further divided into 1 h,6 h,12 h,18 h and 24 h subgroups,with 6 animals at each time point.Tissue microarray and immunohistochemistry were used to examine the expression of NF-κB and MMP2/TIMP-2 in different groups.Results: MMP-2 and NF-κB began to express 1 h after trauma in TRA group and their expression was significantly stronger than that in the control group(P<0.05,P<0.01); their expression reached the peaks at 12 h and 6 h after trauma and then gradually decreased.The expression of MMP-2 and NF-κB in UTI group reached their peaks 18 h and 12 h after trauma,respectively,and was significantly higher than that in the control group(P<0.01),but was lower than that in the TRA group at corresponding time points(P<0.01,P<0.05).The expression of TIMP-2 was significantly stronger than that in the control group and TRA group at 6 h,12 h and 18 h after trauma(P<0.01,P<0.05).Conclusion: The expression of NF-κB,MMP-2 is increased in acute