A 17-year-old girl presented with signs of increased intracranial pressure. On computed tomography, an enhancing intraaxial lesion in the region of the foramen magnum was demonstrated. Surgical excision was performed. The pathological diagnosis was low grade fibrosarcoma. Her subsequent course was complicated by cerebrospinal fluid seeding, a posterior fossa recurrence, and repeated subarachnoid hemorrhage with cerebral vasospasm. A combination of radiotherapy and intraventricular chemotherapy has left the patient symptom-free 2 years after operation. The intramedullary appearance of fibrosarcoma and the unusual subsequent clinical course are discussed.