The authors report a primary intramedullary spinal cord lymphoma in a 49-year-old man who presented with right arm pain, voiding difficulty and progressive walking difficulty. Preoperative cervical spinal CT and MRI studies were highly suggestive of spinal stenosis with compressive myelopathy but histopathological study of the specimen after surgery revealed spinal cord lymphoma. As no tumorous lesion was found other than the spinal cord, he was given 6000 rad of radiation under the diagnosis of primary CNS lymphoma. The neurologic deficits improved partially after the surgery but delete right arm pain persisted. One year later, follow up studies showed neither local nor systemic tumor recurrence.