Cor pulmonale (CP) is a pathologic condition related to the right heart chamber and is the consequence of its accute intermittent or chronic overloading as a result of a high mean pulmonary arterial pressure. The term cor pulmonale acutum is used, if the stress is of duration of hours or days. It occurs mostly in massive pulmonary thrombotic or non - thrombotic embolias and may be fatal. Cor pulmonale chronicum means hypertrophy of the right heart ventricle, occuring in long standing diseases disturbing the function and/or structure of the lungs, thoracic cage and pulmonary vessels. Consequent upon the strain of forcing blood through the pulmonary vascular system, it may have an hypoxic, vascular or restrictive form. Diagnostics of cor pulmonale is based on history taking, physical examination, instrumental and other investigations, as X- ray, ECG, computer tomography (CT), spiral CT, high resolution CT, echocardiography, lung function tests, ventilation and perfusion scintigraphy of the lungs, right heart catheterisation, pulmoangiography, etc. Treatment consists of therapy of the underlying disease, treatment of pulmonary hypertension and heart failure. Improving alveolar ventilation, oxygenotherapy, diuretic and cardiotonic treatment are the essentials ot this therapy. Pharmacotherapy includes anticoagulant drugs, synthetic prostacyclins and their analogs, calcium chanel blockers, endothelial receptor antagonists, phosphodiesterase inhibitors of type 5, and others. Administration of diuretics my become dangerous, because potassium depletion in combination of hypoxaemia, use of sympathomimetics and overloading of the myocard may cause fatal dysrytmias. In the pharmacotherapy of CP calcium chanel blockers, endotelial receptor antagonists, phosphodiesterase inhibitors of type 5, and other drugs are also used. Cardiac cirrhosis of the liver, secondary hyperaldosteronism, compensatory polyglobulia, elevated haematocrit and high blood viscosity my occur as complications of the disease.