The prognosis of osteosarcoma with brain metastasis is very poor. We report a 14-year-old girl with osteosarcoma of the right distal femur who is alive and free of disease 6 years after the craniotomy and irradiation for brain metastasis. This longterm survival is attributed to the absence of active pulmonary metastasis at the onset of brain metastasis and the complete removal of the brain metastasis by craniotomy. Patients without active pulmonary metastasis at the onset of brain metastasis may achieve longterm survival. In such patients, it would be worthwhile to perform craniotomy aggressively.