[en] The development of chronic obstructive pulmonary disease (COPD) and the frequent inflammatory exacerbations with development of respiratory failure lead to changes in the micro circulatory and an increased risk of lung thrombotic and thromboembolic complication. The aim of the study was to establish the possibility of the perfusion lung scanning and diffusion capacity for early diagnosis of pulmonary micro circulatory disturbances in COPD with mild and moderate respiratory failure. 59 COPD patients were investigated. The data presented significant segmental disorders. Only in 5 (8.47%) of them the perfusion lung scintigrams were normal. In 23 of the patients, single-breath diffusing capacity (DICO) and its two components: membranous component (Dm) and capillary blood component (Vc) were determined. DICO was lower especially Vc the mean sign of micro circulatory disorders. A relationship between the degree of hypoxaemia and the changes found in the perfusion scintigraphy was found. Changes in the pulmonary lung scanning and in the diffusion capacity in COPD with mild respiratory failure seem to be an early diagnostic test. The early anticoagulant and desaggregant prevention may decrease the risk of thrombotic complications in the development of the disease. (authors)