Currently, COPD is considered as a systemic pathology. Cardiovascular disorders are distinguished among extrapulmonary manifestations, the earliest manifestations of which are endothelial dysfunction. However, in the literature there is ambiguity of data proving the influence of anamnestic, clinical parameters of COPD on the formation and progression of endothelial dysfunction. The aim of the study was to study the relationship between the concentration of NO in the exhaled air in patients with COPD and some clinical and anamnestic parameters of their disease, depending on the stage and phase of the pathological process. 25 male patients with COPD stages I-IV in remission and exacerbation were examined; the control group included 11 practically healthy individuals. A correlation was established between the concentration of NO in the exhaled air and the duration of the disease (r = -0.67, p=0.02) in patients with COPD stages III-IV during exacerbation, which may indicate the formation and progression of endothelial dysfunction with an increase in the duration of the disease. At the same time, in the remission phase in this contingent, the concentration of NO in the exhaled air did not depend on the studied parameter. Regardless of the stage and phase of the pathological process, age, the frequency of exacerbations per year, in patients with COPD indicators of external respiration function do not affect NO concentration in the exhaled air and, accordingly, are not significant parameters that determine the level of the studied marker among presented contingent.