Tibial agenesis with femoral duplication (Gollop-Wolfgang complex) and cloacal exstrophy are each rare malformations. Thus, their concurrence in an individual is an extremely rare event. We report on a patient born with distal duplication of the right femur, agenesis of the right tibia and hallux, cloacal exstrophy, and sacral defects. Review of the small group of cases reported with femoral duplication and tibial agenesis in association with caudal midline defects demonstrated a pattern of anomalies that while varying in presentation and severity was quite specific. We postulate that this disorder is related to misexpression of one or more distal HOX genes, potentially HOX10 or HOX11, leading to abnormal induction and proliferation of caudal mesenchyme.