AIM:The generation of oxygen free radicals has beenimplicated in the pathogenesis of experimental pancreatitis.The aim of this study was to determine the role of oxygenfree radicals in patients with acute pancreatitis.METHODS:The plasma levels of C-reactive protein(CRP),lipid peroxide(LPO),myeloperoxidase(MPO)and superoxidedismutase(SOD)were measured in 13 patients with acutepancreatitis and 14 healthy volunteers.RESULTS:Among the patients with acute pancreatitis,therewere higher plasma levels of LPO and MPO and lower SODactivity in patients with severe pancreatitis than in thosewith mild pancreatitis.However,there was no significantdifference in the serum marker of oxidative stress no matterwhat the etiology was.The LPO level was especially correlatedwith the concentration of serum CRP and CT severity index.CONCLUSION:The oxygen free radicals may be closelyassociated with inflammatory process and the severity ofacute pancreatitis.Especially,the concentration of plasmaLPO is a meaningful index for determining the severity ofthe disease. AIM: The generation of oxygen free radicals has been disseminated in the pathogenesis of experimental pancreatitis. AIM of this study was to determine the role of oxygen free radicals in patients with acute pancreatitis. METHODS: The plasma levels of C-reactive protein (CRP), Among the patients with acute pancreatitis, therewere higher plasma levels of LPO and MPO and lower SODactivity in patients with Severe pancreatitis than in those with mild pancreatitis. Even before there was no significant difference in the serum marker of oxidative stress no matter what the etiology was. LPO level was especially correlated with the concentration of serum CRP and CT severity index. CONCLUSION: The oxygen free radicals may be closely associated with inflammatory process and the severity ofacute pancreatitis .Especially, the concentration of plasmaLPO is a meaningf ul index for determining the severity ofthe disease.