Doppler-based sonography investigation of liver blood circulation plays major role in the modern diagnosis of portal hypertension that is frequently caused by portal vein thrombosis. Eight patients with portal vein thrombosis have been investigated. During the sonographic investigation we evaluated the size of liver, focal changes in liver, the diameters of the portal vein and its both branches, of the spleen vein, of the superior mesenteric vein, the direction and the characteristics of the blood flow, portaportic and portasystemic collaterals, and the size of spleen. The thrombosis of the trunk and both branches of the portal vein was detected in 4 patients, out of which there was one case of additional thrombosis of the spleen and the superior mesenteric veins, while in another case there was partial thrombosis of the spleen vein. A separate thrombus of the portal vein trunk was noticed in 1 patient. The thrombosis of the portal vein trunk and the right branch was diagnosed in 1 case. There were 2 cases of thrombosis of only left branch of the portal vein. The cause of the portal vein thrombosis remained undetected in 6 cases. The thrombosis of the portal vein developed as a consequence of pancreatitis in one patient, the cause of another case was hepatocellular carcinoma. In comparison to CT, sonography is able to determine additionally the direction of the blood flow and to record a variety of different sections in detecting the above-mentioned pathology. Doppler-based sonography investigation of liver blood circulation, especially the color-coded, is non-invasive, it can be carried out quickly and does not need expensive contrast medium.