A case is reported of bilateral coronoid hyperplasia. The literature is reviewed concerning this condition's etiology, pathogenesis, clinical characteristics, diagnosis, and treatment. Jacob disease and coronoid elongation are both clinical features of coronoid hyperplasia. It is usually accompanied by restricted opening. The etiology and pathogenesis of coronoid hyperplasia are unclear. The condition can be diagnosed by panoramic radiographs and with 3-dimensional reconstructions from computerized tomography image data sets. Hyperplasia of the coronoid processes can be treated using an intraoral approach for coronoidectomy and dynamic laser physiotherapy after surgery. Although hyperplasia of the coronoid processes is uncommon in clinic, it can be found through careful examination and proper radiographic study. A 39-year-old female patient was referred for coronoid hyperplasia (Jacob disease on right and elongation on left). The histologic diagnosis for the right condylar condition was osteochondroma.