Not all patients seeking autogenous breast reconstruction have sufficient donor tissue for a bilateral reconstruction. Identical twin isotransplantation, as a model system for allotransplantation without immunologic barriers, broadens the definition of "spare parts" surgery. In this case, we demonstrate the simultaneous transplantation of both autogenous and syngeneic deep inferior epigastric perforator flaps for bilateral breast reconstruction. As our understanding of immunology evolves, allotransplantation may further increase our reconstructive options for other postmastectomy patients.