Primary intraventricular hemorrhage (PIVH) imaged by magnetic resonance imaging (MRI) is reported. A fifty-seven-year-old man with long-standing hypertension suddenly developed severe headache, vomiting, and retrograde amnesia. A computed tomography scan on the same day revealed hematoma in the right posterior horn of the lateral ventricle and in the 4th ventricle. Angiography of the neck and head failed to demonstrate any vascular abnormalities. On the second day his neurological symptoms almost recovered except for the loss of the memory of the ictal day. High-field MRI on the sixteenth day demonstrated an isointense lesion surrounded by a hypointense area in the T1 weighted image or a hyperintense lesion in the T2 weighted image, suggesting subacute hematoma consistent with hypertension, just anterior to the right trigone of the lateral ventricle.