Three patients initially diagnosed with benign giant cell tumors of bone who had lung metastases develop were treated with whole-lung radiotherapy as part of the therapeutic treatment of their distant disease. External beam therapy to 16 Gy in 10 fractions was delivered to the whole lung, with a boost of 35 to 45 Gy to sites of gross metastatic disease. One patient's lung metastases progressed after treatment, and the patient soon died. The two other patients were long-term survivors (7.5 years and 13 years) with complete resolution of detectable disease. One of the two patients required two additional courses of local radiation to metastatic sites. The authors therefore recommend whole lung radiotherapy to 16 Gy with an additional boost to 35 to 45 Gy to gross disease as an option for patients with pulmonary metastases who are poor surgical candidates, who refuse thoracic surgery, whose disease is technically unresectable, or whose disease recurs or progresses after surgery or chemotherapy.