We describe two patients who developed myelopathy 15 and 27 months after allogeneic marrow transplantation. Exacerbations of the myelopathy occurred, with the development of optic neuropathy in one patient when corticosteroid therapy was tapered. The other patient had two exacerbations, 28 months and 40 months after transplantation, both of which resolved with plasma-pheresis. These case reports suggest that immune-mediated disease after transplantation can affect the central nervous system.