A three year old, intact female, coastal carpet python (Morelia spilota mcdowelli) was diagnosed with osteosarcoma and treated with a palliative course of radiation therapy. The snake originally presented with a pathologic fracture of a precaudal vertebra. Over six months a mass slowly grew evidenced by a mass effect dorsal to the vertebral fracture, and the snake became anorexic and obstipated. An incisional biopsy from the center of the mass was histologically consistent with osteosarcoma. The snake was treated with a standard palliative radiation therapy protocol. Following treatment the snake began eating and defecated again. Six months after treatment, however, the snake became anorexic and obstipated and was euthanized. Histopathology of the tumor on necropsy showed few neoplastic cells and extensive necrosis and fibrosis within the tumor, indicating that the tumor had responded to radiation therapy.