Portal vein thrombosis is a frequently encountered complication in hepatology and hematology. In patients with liver cirrhosis, it can occur in the natural history of the disease due to clotting disorders or associated with hepatocellular carcinoma. The development of a malignant thrombus is a contraindication to several therapeutic procedures in liver cancer, such as liver resection or transplantation or transarterial chemoembolization; therefore, patients need to be attentively evaluated. Contrast-enhanced ultrasonography is a relatively new noninvasive imagistic investigation with proven accuracy in focal liver lesions. Its use in differentiating malignant and nonmalignant portal vein thrombosis is still controversial. This article revises the characteristics of portal vein thrombosis on contrast-enhanced ultrasonography in order to determine its accuracy in the diagnosis of malignant portal vein thrombosis.