Aim. To evaluate endothelial function in patients with chronic ischemic heart disease by determining the number of circulating endothelial cells in peripheral blood. Material and methods. 71 patient with typical angina class I-III and presence of obstructive coronary artery disease according to coronary angiography were assessed, coronary anatomy was assessed on the SYNTAX Score scale and the number of CEC was determined by flow cytofluorimetry. Depending on the chosen treatment strategy patients were divided into the following groups: a group of medical therapy (group 1) - 22 patients; a group of patients requiring percutaneous coronary intervention (group 2) - 25 patients; a group of patients requiring surgical revascularization by coronary artery bypass surgery (group 3) - 24 patients. The control group consisted of 20 patients without atherosclerotic lesions of the coronary arteries. Results. Study groups do not differ by sex, age, history of smoking, the presence of hypertension, MI history (р > 0.05). In the group of patients who are scheduled to perform CABG significantly more patients with diabetes mellitus (р < 0.05) (group 1 - 3 patients (13.6%), group 2 - 4 patients (16.0%), group 3 - 7 patients (29.1%), control group - 2 patients (11.8%)). Study groups reliably differ in the anatomy of coronary lesions (SYNTAX Score in group 1 - 9.4 ± 2.7, in group 2 - 19.7 ± 5.7, in group 3 - 23.5 ± 6.0), р < 0.05. The number of CECs in the study groups is significantly higher than the generally accepted norm (р < 0.05), (group 1 - 12 (10÷16), group 2 - 14 (10÷17), group 3 - 14 (11÷17), control group - 12 (10÷16)). There are no significant differences between the groups with coronary artery disease (р > 0.05). Conclusion. Study of endothelial function by flow cytometry using monoclonal fluorescently labeled antibodies to CD146 and CD45 can be considered as a criterion for noninvasive assessment of the severity of atherosclerotic lesion of the coronary bed. (For citation: Sayganov SA, Kuzmina-Krutetskaya AM. Endothelial dysfunction and circulating endothelial cells in patients with chronic ischemic heart disease. Herald of North-Western State Medical University named after I.I. Mechnikov. 2018;10(2):27-32. doi: 10.17816/mechnikov201810227-32).