The results of examination and treatment of 647 patients with endogenous hypercortisolism were studied: pituitary corticotropinoma was detected in 494 (76.4%) patients, corticosteroma and pre corticosteroma of the adrenal gland in 142 (21.9%), bilateral macro-nodular hyperplasia of the adrenal glands of primary adrenal origin-in 11 (1.7%). Differential diagnosis of clinical forms of endogenous hypercortisolism was based on the assessment of the level of adrenocorticotropic hormone and cortisol, both in peripheral blood, and with selective bilateral blood sampling from the adrenal veins and lower stony sinuses, and the study of the nature of samples with 8 mg of dexamethasone. Topical diagnostics consisted in assessing the state of the adrenal glands and pituitary gland during computed tomography and magnetic resonance imaging with the use of contrast agents, and the use of special software 3D-Volume Rendering Technique allowed optimizing tactical and technical approaches to performing surgical interventions. Of the operated patients with adrenocorticotropic hormone dependent endogenous hypercortisolism, total removal according to the control magnetic resonance imaging was achieved in 92.3% of cases, subtotal in 7.7%. However, hormonal remission was achieved only in 82.4% of cases. All patients with corticosteroma and pre-corticosteroma of the adrenal gland underwent adrenalectomy: in 6 patients by open method, in 136 patients by endovideosurgical method (in 11 patients by laparoscopic method, in 124 patients by retroperitoneoscopic method, and in 1 patient by thoracoscopic transdiaphragmatic adrenalectomy). In all patients, the operation led to recovery. Patients with benign macronodular hyperplasia of the adrenal glands needed conservative treatment with steroidogenesis blockers. Indications for surgical treatment in the volume of unilateral adrenalectomy occurred only in 2 patients.