The oxidant and antioxidant status of 42 patients with pyloroduodenal ulcers aged 17-46 years was examined before and after traditional hospital treatment.

Total oxidative activity and plasma concentrations of lipid hydroperoxides and malonic dialdehydes were higher in the patients before therapy than in the controls, this increase correlating with the disease duration.

Total antioxidative activity and catalase of erythrocytes were decreased only in the patients with ulcer relapses, whereas in the patients with primary ulcers, these values were virtually normal.

Erythrocyte superoxide dismutase activity was reduced in all the patients.

Low activity of this enzyme negatively correlated with the disease duration.

The treatment led to evident clinical and endoscopic improvement but did not completely normalize the increased level of free-radical oxidation parameters and decreased total antioxidative activity and erythrocyte catalase and superoxide dismutase activities.