Massive osteolysis (Gorham-Stout syndrome) is a rare condition of unknown aetiology that is thought to result from a localised endothelial proliferation of lymphatic vessels resulting in destruction and absorption of bone. The diagnosis of Gorham-Stout syndrome can be made only after first excluding osteolysis from infection, inflammation, endocrine disease, and cancer. The syndrome is rarely seen in the facial skeleton and has a variable prognosis. Many treatments have been advocated but only surgery and radiotherapy have had some success. We present a case of massive osteolysis of the entire mandible, which was reconstructed with a free vascularised fibular graft and bilateral prosthetic replacements of the temporomandibular (TMJ) joints. Four years later the fibular graft had been absorbed requiring further reconstruction with another fibula graft.