The investigation and treatment of a pregnant thalassemic woman who developed severe paraplegia is presented. Magnetic resonance imaging showed a paravertebral mass infiltrating the epidural space, resulting from extramedullary hematopoiesis (marrow heterotopia). The patient was treated successfully with repeated blood transfusions and made a complete recovery. The literature (36 cases) is reviewed and the magnetic resonance imaging features of spinal extramedullary hematopoiesis are presented. The efficacy of transfusions in the management of spinal cord compression due to marrow heterotopia in thalassemic patients is discussed.