Background: The purpose of this study was the clinical, functional and instrumental evaluation of efficacy and safety of angiotensin-I receptor blocker Valsartan in patients with chronic obstructive pulmonary disease. Material and methods: There were investigated 25 patients (mean age 50.5 ± 4.34 years) with moderate to severe forms of obstructive lung disease – initial and after 5 weeks of treatment with angiotensin – I receptor blocker Valsartan (Nortivan, ,,Gedeon Richter’’, Hungary), mean dose 54.5 ± 15.4 mg once-daily, using standard ECG, EchoCG with Doppler, bodyplethysmography, ultrasound Doppler (for endothelial function estimation), pulmonary diffusion capacity for CO, cycloergometry - initial and after short – term treatment with Nortivan. Results: There were not detected any negative changes on bronchial permeability after the treatment. Significant improvement of endothelial function, pulmonary diffusion capacity, parallel with considerable decreasing of pulmonary artery systolic and mean pressure and total bronchial resistance – were observed after 5 weeks of treatment.