An allogeneic muscle transfer was used to cover a large cranial defect in one of a pair of craniopagus twin separated a decade ago. Both separated twins died, 7 months apart, with the twin that had received the transfer dying first. The cause of death was generalised cytomegalovirus infection. An autopsy showed extensive brain necrosis caused by vascular insufficiency, a result of the abnormal vascular anatomy at birth. The muscle allograft showed no signs of rejection. Progress in immunosuppressive treatment over the last decade, which has enabled successful allogeneic nerve grafts and composite-tissue transplantations, might make muscle transplantation for the coverage of large defects, with and without functional demands, feasible in the future.