Portal vein thrombosis is a rare condition occurring in association with a wide variety of precipitating factors. Among these, liver cirrhosis and neoplasm constitute the major etiology of portal vein thrombosis. In oriental countries, as compared with western countries, liver cirrhosis has been reported to be extremely rare cause of portal vein thrombosis. The authors experienced a case of portal vein thrombosis in a 46-years-old man with liver cirrhosis who admitted to our hospital due to abdominal pain. Abdominal CT, angiography and laparotomy showed involvement of portal vein with thrombus and there were no evidences of neoplastic disease. The screening tests for hypercoagulable states were normal. The patient was treated with portal vein thrombectomy and anticoagulation therapy. We report this case with brief review of literature.