Osteomas are benign, slow-growing osteogenic tumours rarely occurring in the craniofacial bones. Osteomas are characterised by the proliferation of compact and/or cancellous bone. It can be of a central, peripheral, or extra skeletal type. The peripheral type arises from the periosteum and is rarely seen in the mandible. The lingual surface and lower border of the body are the most common locations of these lesions. They are usually asymptomatic and can be discovered in routine clinical and radiographic examination. In this paper, the authors present a large solitary peripheral osteoma located in the inferior surface of the left angle of mandible and causing facial deformity in a 14-year-old boy. Radiographic examination by diagnostic radiographs revealed mixed appearance (radiopaque- radiolucent), well-circumscribed, pedunculated mass approximately 3.5 cm in size. The osteoma was removed surgically, and no recurrence has been observed.