Introduction. The hepatic arterial and portal venous blood flows have the role of maintaining a constant total hepatic perfusion and ensuring the oxygen requirement. The primary role has nitric oxide, because the portal venous and hepatic arterial endothelial cells contain NO-synthase. Vascular resistance can change both in the portal system and in the hepatic arterial system. Material and methods. The study included 46 patients-32 men, 14 women, average age-39±0.21 years. Linear parameters studied by color Doppler. Results. The study of the blood parameters in the liver vessels established the increase in the resistance index in the hepatic artery by 1,4%, the increase in the pulsation index by 6,3%, the volume of the blood flow speed in the portal vein by 7,7%. Dilation of the diameter of the hepatic artery was observed in 65% of the patients, associated with a decrease in the diastolic speed (38%) and a increase in the volume speed (57%) of the blood flow. The spatial speed of portal bood flow in group I increased to 990± 69 ml/min, of the group II was 1188±34 ml/ min. Conclusions. Nitric oxide increase vascular resistance in both portal and hepatic arterial system. The ptogressive increase in the resistance index of the hepatic artery in patients indicates increasing intrahepatic vascular resistance.