Non-obstructive coronary artery disease is generally considered as a favorable type of pathology, however, a number of studies indicate that in non-obstructive atherosclerosis, the risk of such cardiovascular events as myocardial infarction, ischemic stroke, sudden cardiac death and decompensated heart failure cannot be completely ruled out. This may be due to microvascular dysfunction. However, due to the small diameter of vessels, none of the imaging techniques used in clinical practice makes it possible to assess microvascular morphology. To date, the most well-established methods for assessing myocardial perfusion are single-photon emission computed tomography (SPECT) and positron emission tomography (PET). The ability to quantify myocardial blood flow and coronary flow reserve allows SPECT and PET to be the methods of choice for non-invasive diagnosis of microvascular dysfunction. This review is devoted to current data on the clinical significance of radionuclide diagnosis of microvascular dysfunction in patients with non-obstructive coronary artery disease.