Extramedullary hematopoiesis (EMH) in the spinal epidural space is a rare but treatable cause of progressive paraparesis in patients with a variety of hematological and systemic disorders. We report a case of extensive thoracic epidural EMH causing progressive spastic paraparesis in a patient with agnogenic myeloid metaplasia. The literature describes 11 additional cases of myelopathy due to epidural EMH. All patients had EMH in the midthoracic region with elevated cerebrospinal fluid protein and abnormal spine roentgenograms or myelograms. Treatment with decompressive laminectomy, radiation therapy, or both, resulted in marked or complete recovery in 7 of 10 patients. Patients who develop paraparesis and who have a disorder associated with EMH should be evaluated rapidly for this treatable condition.