A case of idiopathic portal hypertension (IPH) associated with systemic lupus erythematosus (SLE) is reported in a 38-year-old man who had been diagnosed with SLE and treated for 18 years. Esophageal varices. found in 1994 on endoscopic examination, had been followed up for 2 years. On July 16, 1996, he was admitted to Nagoya University Hospital because there was a high risk of bleeding from the esophageal varices due to severe thrombocytopenia. As partial splenic embolization had temporarily controlled the thrombocytopenia, splenectomy and devascularization of the stomach vessels were performed after endoscopic ligation of the esophageal varices. Histological specimens of wedge biopsied liver showed chronic inactive hepatitis without cirrhosis. The presence of anticardiolipin antibody, indicated by positivity for lupus anticoagulant, was suggestive of the presence of a common immunological mechanism in the etiology of SLE and IPH.