During a routine annual physical examination, a small, hard, palpable mass was discovered on the left cheek below the lateral canthus of the eye of an adult male squirrel monkey (Saimiri sciureus). Radiographs of the lesion were obtained, and the lesion was surgically removed. Histologic examination of the mass was performed. On the basis of radiographic, anatomic, and histologic findings, a diagnosis of osteoma was made.