AIM:To observe the changes in oxygen free radical (OFR) and the curative effect of traditional Chinese medicine Qing Yi Tang in acute necrotizing pancreatitis (ANP).METHODS:After induction of ANP by injection of sodium taurocholate into pancreatic duct, 16 dogs were randomly divided into control group and Chinese medicine group.Serum amylase, SOD and MDA were determined on postoperative day 1, 2, 4 and 7. The animals were sacrificed on day 7. SOD and MDA in organs were determined, and pathological changes in pancreas were observed.RESULTS: As compared with control group, the serum level of amylase (734U/L vs 2783U/L) and MDA (7.8nmol/ml vs 14.8nmol/ml) in Chinese medicine group were decreased on day 7 (P < 0.05), while SOD increased significantly (281nU/ml vs 55nU/ml, P < 0.01), and similar changes occurred in MDA and SOD in organs, especially in the pancreas; the pathological changes in the pancreas were alleviated as well.CONCLUSION: Qing Yi Tang is effective in clearing OFRs and alleviating pathological changes in ANP.