Aim of the study. To determine parameters of ventilatory function and acid-base balance in patients with chronic heart failure after myocardial infarction and to evaluate effects of perindopril on these parameters. Material and methods. 25 nonsmokers and 15 smokers with NYHA class III-IV heart failure. Ventilatory function (spirometry) and acid-base balance in capillary and venous blood were studied before and after 6 months of therapy with perindopril. Results. Initial parameters of ventilatory function were lower compared to predicted values in both groups but especially in smokers. In nonsmokers treatment with perindopril was associated with significant decrease of vital capacity (by 14,3%, p<0,05) while changes of other parameters of ventilatory function were not significant. In smokers there was a tendency to improvement of bronchial resistance. Initially all patients had compensated respiratory acidosis. Therapy was associated with significant decreases of pCO2 in capillary and venous blood (25,5%, p<0,05, and 18,2%, p<0,05, respectively,) and of capillary to venous blood sO2 ratio (48,3%, p<0,05).