Objective:To investigate the effect of recombinant staphylokinase (r-Sak) and the Chinese medicine Yihuo Qingyi Decoction (益活凊胰汤 Herbal decoction for severe acute pancreatitis) in the treatment of the severe acute pancreatitis (SAP) in rats,and to observe the synergistic effect of the two.Methods:One hundred and sixty-two adult male SD rats with the body mass of 250-280 g were randomly divided rninto the following 5 groups:sham operation group (n=18),control group (n=36),Yihuo Qingyi Decoction treatment group (n=36),r-Sak treatment group (n=36),and Yihuo Qingyi Decoction plus r-Sak treatment group (n=36).The SAP ratmodel was prepared by retrograde injection of 5% sodium taurocholate into the cholangiopancreatic duct.Two days before modeling,Yihuo Qingyi Decoction was intragastrically administrated,and r-Sak was intraperitoneally injected.The survival rate within 18 h after modeling was determined.The pancreatic blood flow,the weight of ascites,and the serum amylase and lipase were investigated at 6 h,12 h,and 18kh after modeling,and the pancreatic tissue was examined under light microscopy to see its pathological change.Results:The 18 h survival count of group A,B,C,D and E rats was 9,2,6,7 and 8 respectively.After r-Sak and Yihuo Qingyi Decoction intervention,the serum amylase and lipase and the weight of ascites were significantly decreased,especially in group E.18 h after modeling,the level of the serum amylase and lipase and the weight of ascites in group E was 1 100±118 U·L-1,1 000±150 U·L-1 and 13.40±1.80 g respectively,obviously lower than that of group B (P<0.05).After SAP was induced,the pancreatic blood flow showed a tendency to decrease,but the decrease extent in the treatment groups was smaller than that in the control group.18h after modeling,the pancreatic blood flow in group B and group E was 30.16±8.96 mL·100 g-1 ·min-1,and 129.10±42.58 mL·100 g-1 ·min-1 respectively,there was significant difference (P<0.05).The pathological change of the pancreatic tissue was alleviated in the treatment groups.Conclusion:Both r-Sak and Yihuo Qingyi Decoction play a beneficial role in the treatment of rat SAP and there is a synergistic effect between the two.