Effect of carvedilol on the antioxidative enzymatic defence was investigated in patients with stable angina. The study comprised 27 patients (20 men and 10 women), aged 38-55 years (mean 48.3 years) with stable angina. The patients were administered carvedilol in increasing every four weeks doses: 12.5 mg/day, 25 mg/day, 50 mg/day. The control group consisted of 12 healthy subjects aged 39-49 years (mean 45.7 years). Blood samples were collected before and 4, 8 and after 12 weeks of therapy in patients and once in control group. Our study has been approved by the local Ethics Committee. Superoxide dismutase (SOD-1), glutathione peroxidase (GSH-Px) and catalase (CAT) activities in erythrocytes were determined according to Misra and Fridovich, Little and O'Brien and Beers and Sizer; respectively. The enzymatic antioxidative defence was significantly decreased in patients with stable angina in comparison to healthy subjects. During carvedilol therapy an increase in SOD-1, GSH-Px and CAT activities was observed. Moreover GSH-Px activity after 8 and 12 weeks of carvedilol therapy did not differ from that observed in group of healthy subjects. The results of our study have shown that carvedilol enhances antioxidative enzymatic defence in patients with stable angina.