Background. The maximum duration of vascular access for hemodialysis functioning rarely exceeds 4 years. The main tool for diagnosing access dysfunction is duplex ultrasound. Dynamic ultrasound examination of vascular access is not included in the standard examination of patient undergoing hemodialysis in Russia.Objective. To study the structure of complications and changes in hemodynamics in the vascular access for hemodialysis and to determine the risk factors contributing to its development.Design and methods. Ultrasound, clinical and laboratory examination was performed in 550 patients undergoing program hemodialysis, 517 (94.0 %) of them had arteriovenous fistula, 33 (6.0 %) patients had arteriovenous graft.Results. Vascular access complications occurred in 26.7 % (147 patients), there was no significant difference in the detection rate of thrombosis (26.5 %), stenosis (23.8 %), and aneurysm (21.1 %). A combination of two complications was observed in 20.4 %, the steal syndrome — in 8.2 %. A correlation was established between the presence of significant stenosis, aneurysm of the outflow vein and the development of thrombosis, between the presence of concomitant diseases of the peripheral arteries and the development of steal syndrome and stenosis of the inflow artery and the anastomosis zone.Conclusion. Duplex ultrasound allows to diagnose complications of vascular access for hemodialysis and determine its causes.