Meningeal myeloid metaplasia (MM) is very rarely observed in patients with myelofibrosis. We report the occurrence of meningeal MM causing exophthalmus and fever in a patient with myelofibrosis secondary to polycythemia vera. A computerized tomography (CT) scan showed multiple intracranial and intraorbital enhancing masses. A needle aspirate of retrobulbar space confirmed the diagnosis of extramedullary hematopoiesis. The patient subsequently developed a rapidly worsening tumor-like syndrome with hemiparesis, aphasia, and loss of sphinteric control. The administration of radiotherapy caused a complete and stable regression of clinical symptoms and a marked reduction of MM masses.