The purpose of the study was to determine the effect of the angiotensin receptor blocker lozartan on clinical manifestations, gas transport, and metabolism in blood cells in patients with chronic cor pulmonale (CCP). The subjects were 53 patients with chronic obstructive bronchitis (COB) and secondary functional claa III pulmonary hypertension. Use of lozartan in complex therapy of these patients led to increase of pyruvic acid content in erythrocytes and glucose-6-phosphatdehydrogenase activity, which suggests that lozartan stimulates redox processes in blood cells. This significantly improves metabolic provision of erythrocyte functioning, phagocytosis and immunogenesis, and leads to favorable clinical effect in patients with COB and CCP.