We report a 73-year-old woman with intravascular malignant lymphomatosis (IML) who showed generalized telangiectasia as well as various neurological symptoms. In July 1998, she developed fever, dizziness, and confusion followed by left hemiparesis, and was admitted to our hospital on August 11, 1998. Laboratory tests indicated a normochromic normocytic anemia, thrombocytopenia, elevated serum lactic dehydrogenase (LDH), C-reactive protein (CRP), and cerebrospinal fluid protein. Magnetic resonance imaging (MRI) of the brain revealed an infarct-like lesion in the left frontal lobe and multiple white matter lesions. After admission, her neurological status deteriorated and lapsed into coma and quadriplegia. At the end of September 1998, generalized telangiectasia appeared, and she was diagnosed as IML on skin biopsy. Although combination chemotherapy failed to improve her neurological symptoms, telangiectasia disappeared in a few days, and the infarct-like lesion on MRI decreased in size. Serum LDH, CRP, and thrombocyte counts were normalized. Autopsy findings revealed perivascular clustering of B cell type lymphoma cells in the left frontal lobe where abnormal signal intensity was found on MRI, as well as the spleen and the bone marrow. This case emphasizes the importance of early diagnosis and treatment in IML.