A 34-year-old Japanese woman developed subcutaneous induration in the left thigh, then showed extreme eosinophilia, and died of hemorrhagic infarction of the brain. Autopsy revealed endocarditis with eosinophil infiltration and systemic thrombophlebitis, including pulmonary veins and intrahepatic branches of the portal vein. Arterial structure was relatively preserved. She had no clinical history of asthma and had anti-ascarid IgE antibody at postmortem serological examination; thus, her disease does not fulfill the diagnostic criteria of Churg-Strauss syndrome and idiopathic hypereosinophilic syndrome (HES). Her organ involvement is, however, consistent with that of HES; thus, her pathophysiological conditions would resemble those of HES. Systemic thrombophlebitis without arterial lesion in patients with hypereosinophilia has never been reported, and this case would broaden the spectrum of vascular lesions in these patients.