Objective To investigate the clinical characteristics of the patients with portal hypertension secondary to primary myelofibrosis (PH-PMF). Methods The clinical data of patients with PH-PMF retrieved from Peking University Third Hospital were collected and analyzed. Results A total of 6 from illness onset to definite diagnosis was 24 months. The symptoms related to portal hypertension included bloating, abdominal mass, hematemesis and melena. The signs related to portal hypertension included splenomegaly ( moderate or severe in all patients), hepatomegaly ( mild or moderate in most of patients),shifting dullness positive and varices in abdominal wall. Only a small portion of patients had jaundice, liver palms and spider angioma. The indexes related to liver functions were normal or only mild abnormal in most cases. The average diameters of portal vein and splenic vein were ( 16. 0 ±3.2) mm and ( 11.0 ±3.4) mm,respectively. Thrombosis of portal vein or splenic vein was found in 2 cases. Liver biopsy revealed extramedullary hemopoiesis in one patient. In addition to medicine therapy related to portal hypertension in 5 patients with PH-PMF, 1 patient received splenectomy and another received endoscopic variceal ligation.Conclusions The patients with PH-PMF were clinically rare and easy to be misdiagnosed. The main keys to differentiate PH-PMF from cirrhosis included marked splenomegaly, mild or moderate hepatomegaly, good liver functions, lack of liver palms or spider angioma and extramedullary hemopoiesis showed in liver biopsy samples.