The authors present the state-of-art knowledge concerning the pathogenesis,diagnostic methods,clinical source and treatment of portal venous system thrombosis.It is most often secondary to cirrhosis,primary hepatic tumors and blood hypercoagulability.The clinical presentation depends on the time of development and location of thrombotic lesions.Early stages of portal thrombosis provide indication for thrombolytic and anticoagulant treatment.Chronic thrombosis,most frequently diagnosed, leads to the symptoms of portal hypertension and bleeding from esophageal varices.Patients with portal hypertension due to chronic prehepatic occlusion should be qualified for repeated sclerotherapy of esophageal varices,or,in case of its ineffectiveness,for the formation of peripheral portosystemic shunts.