Hemimandibular hyperplasia (HH) is a rare, self-limiting process manifesting between the first and third decades of life. HH causes facial asymmetry and derangement of the occlusion. Management involves resection of the condylar head and orthognathic surgery. This paper describes the case of a 38-year-old woman with spontaneous onset HH over a span of approximately 30 years. The condition was managed with resection of the condyle with simultaneous orthognathic surgery. The patient is currently satisfied with her appearance and function, and there are no signs of recurrence after 2 years.