A case of bilateral coronoid hyperplasia is presented. This is a developmental abnormality that occurs primarily in males and is characterized by progressive, asymptomatic limitation of mandibular movements. The condition is usually detected shortly after the age of puberty. A diagnosis is usually made on the basis of the history and the radiographic findings. Surgical removal of the elongated coronoid processes, along with good postoperative range-of-motion exercises, will restore full mandibular movement.