<正> The level of lipid peroxides （LPO） and copper-zinc containing superoxide dismutase （SOD-Ⅰ） in the gastric mucosa and serum was determined in 141 samples from 25 patients after con-ventional subtotal gastrectomy （11 cases of Billroth Ⅰ and 14 cases of Billroth Ⅱ） and 11 patientsafter pylorus and antroseromuscular flap preserving gastrectomy （PAFPG）.Those of 11 normal subjects were examined likewise to serve as control.It was found that:（1） The average LPO levelwas much higher and the average SOD-Ⅰ level much lower in the gastric mucosa of the patientsafter conventional subtotal gastrectomy especially the Billroth Ⅱ type than in that of those afterPAFPG.（2） In 36 specimens of stump mucosa

the average LPO level was significantly higher inthe tissue around the anastomotic ring than in that of the body of the stump;no marked differ-ence of SOD-Ⅰ level between the 2 was revealed.（3） The LPO value in the stump mucosa waspositively correlated to and the SOD-Ⅰ value negatively correlated to the pH value of gastric juice.These rindings suggest that the reation of oxygen free radicals in the stump mucosa may be influ-enced by the intragastric pH or by the type of digestive continuity reconstruction

and that thereaction of oxygen free radicals especially the lipid peroxidation may play a role in the pathogenesisof the lesions in the anastomotic stoma.