Introduction. The key point of cardiorenal relationships is the activation of the renin-angiotensin-aldosterone system and the formation of endothelial dysfunction. The aim of our study was to assess the state of endothelium-dependent vasodilation (EDVD) in patients with chronic kidney disease (CKD) as a function of the glomerular filtration rate (GFR). Materials and methods. It was investigated 40 healthy men (mean age 39.2±2.0 years) and 72 patients with CKD I st. (mean age 42.5±11.9 years). GFR was calculated using the formula CKDEPI. Tissue perfusion was studied by high-frequency ultrasound Doppler. Vascular reactivity of the skin was evaluated in functional tests with ionophoresis of acetylcholine. Results. Compared with healthy individuals, the increase in the volumetric blood flow velocity at the 2 minute test with acetylcholine was reduced only at a GFR value of 90-109 ml/min/1.73 m2, with large values of GFR, no indicator changes were detected. Also, only in these patients the most significant violations of oxidative status were noted in the form of an increase in the concentration of diene conjugates in the blood serum, a decrease in the concentration of tocopherol and general SH groups. Conclusions. Disturbance of endothelium-dependent vasodilation in the sample with acetylcholine in patients with the first stage of CKD was established with a GFR value of less than 109 ml/min/1.73 m2. Disturbance of the indicators of oxidative status was noted with a GFR value of less than 109 ml/min/1.73 m2.