A 6 year old, 46.8 kg castrated male Golden Retriever was referred to Cornell's Oncology Service for evaluation and treatment of a cranial mass. The patient had a one month history of trismus, oral pain, and an expanding mass caudal to the left orbit. On physical examination there was a 7.5 x 4.0 x 5.5 cm firm, non-movable mass caudal to the left orbit in the area of the left temporalis muscle. A diagnosis ofmultilobular tumor of bone was made through histopathology and computed tomographic (CT) imaging. The CT scan also showed that the mass was arising from the left coronoid process. Staging with three view thoracic radiographs and abdominal ultrasound revealed no clinically evident metastasis. Surgical excision is the best form of treatment for multilobular tumor of bone and a left zygomatectomy and left coronoidectomy were performed. Two days after surgery the patient was discharged into the care of his owners. Clinical signs had resolved by the two week post-op evaluation.