We report a case of mandibular asymmetry suggested to have delayed growth as a late effect after orthodontic surgery.<BR>Postoperative delayed growth often causes occlusal instability and a poor profile as a late effect. It is difficult to predict such changes because the causes differ from those of general relapse, and development is accidental. Although occlusal instability caused by delayed growth after orthodontic surgery is rare and poorly understood, investigating the details of such changes is of great value for postoperative orthodontics or planning reoperation.<BR>Our findings suggested that changes in mandibular elongation caused by delayed growth differed between the right and left sides. The differences were greatest at the ramus and condyle on the displaced side, showing vertical elongation.<BR>In patients undergoing orthodontic surgery for mandibular asymmetry, the possibility of puberal growth spurts should be considered and patients should be followed up carefully since asymmetry can recur.