Osteosarcoma is a malignant primary tumor of the bone, which is considered rare in birds. This report describes an osteoblastic osteosarcoma in a scarlet macaw (Ara macao), which was apathetic with progressive weight loss, and had a tumor in the distal portion of the femur and proximal tibiotarsus with ulcerated pododermatitis in the contralateral limb. Euthanasia was elected due to poor diagnosis after radiographic and cytological examination. Histopathology and immunohistochemistry were performed and confirmed the diagnosis of an osteoblastic osteosarcoma with hepatic and pulmonary metastases.