Aim. To evaluate the vascular endothelium in patients with cardiopulmonary disease, by studying the levels of endothelin-1 (ET-1) and C-type natriuretic peptide (CNP). Subjects and methods. Examinations were conducted in 212 dwellers of the Astrakhan Region, including 40 patients with chronic obstructive pulmonary disease (COPD) concurrent with hypertensive disease (HD), 40 patients with COPD concurrent with coronary heart disease (CHD), 27 somatically healthy individuals, 35 patients with Stage II HD, 35 patients with Functional Classes II and III CHD, and 35 patients with moderate and severe COPD. Results. The patients with COPD concurrent with HD and CHD were found to have endothelial dysfunction manifesting itself in the overproduction of ET-1 and CNP. The level of CNP was statistically significantly higher in the COPD + HD group than in the HD and COPD groups whereas in the COPD + HD group the level of ET-1 remained comparable to that in the COPD and HD groups. This indicates that CNP is a more sensitive indirect marker of endothelial dysfunction and that nitric oxide deficiency is aggravated in the concurrence of COPD and HD as compared to a mononosological entity (HD, COPD). Conclusion. The concurrence of COPD and CHD is more unfavorable for the development and severity of endothelial dysfunction, which may lead to mutual aggravation syndrome, the rapider progression of the diseases, and the increased frequency of complications.