The aim of this study was to evaluate the effect of carvedilol on the enzymatic antioxidative defence and plasma antioxidative activity in patients with stable angina. The study comprised 30 patients, aged 37-49 years with stable angina. Patients received carvedilol in escalating doses of 12.5 mg/24 h, 25 mg/24 h, and 50 mg/24 h for 4 weeks each. The control group was matched for age and gender, and consisted of 12 healthy volunteers, aged 39-49 years. Blood samples were collected from the cubital vein before and 4, 8 and 12 weeks after the therapy from the patients and once from the control group. For all the subjects, the superoxide dismutase (SOD-1), glutathione peroxidase (GSH-Px), catalase (CAT) activities in the erythrocytes and the antioxidant activity of the blood plasma were determined. The enzymatic antioxidative defence was significantly decreased in patients with stable angina in comparison to the healthy subjects. During the carvedilol therapy, an increase in the SOD-1, GSH-Px and CAT activities was observed. Moreover, 8 and 12 weeks after carvedilol therapy, the GSH-Px activity did not differ significantly from that observed in the group of healthy subjects. Carvedilol also increased the plasma antioxidative activity in patients with stable angina, but its level remained significantly lower than in the control group. In conclusion, carvedilol enhances antioxidant defense mechanisms in patients with chronic stable angina pectoris.