Composite tissue transplantation has been used in the upper extremity with encouraging results. We present a case of hindquarter transplantation in a pair of ischiopagus (united ventrolaterally with a shared lower thorax, abdomen and large conjoined pelvis) conjoined twins separated at three months of age. Each twin had one functionally and aesthetically normal leg and shared a small, deformed, nonfunctional leg. Due to acute decompensation secondary to a lethal and unreparable cardiac anomaly in one of the twins, plans for tissue expansion and delayed separation were aborted. Instead, the fully functional leg and entire hindquarter from the dying twin was transplanted to the surviving sister. The pelvic bones were reconstructed and the limb was revascularized and reinnervated to the healthy twin. Because conjoined twins are syngeneic, no immunosuppressive therapy is required.