Skeletal stability, temporomandibular joint (TMJ)-function, and inferior alveolar nerve function were evaluated in 103 patients with mandibular hypoplasia who were treated with bilateral sagittal split osteotomies to advance the mandible. Stable internal fixation was obtained with miniplates and four monocortical screws. The follow-up period was at least 24 months (average: 32 months; maximum: 60 months). The average B-point advancement was 5.85 mm. Ninety-three patients of 103 (90.3%) had no appreciable relapse at B-point. Eight (7.7%) patients had relapse because of condylar resorption. Maximum mouth opening decreased an average of 1 mm. Sixty-eight percent of the patients with preoperative TMJ-dysfunction symptoms reported improvement or resolution of their symptoms. Sixteen percent experienced worsening of their TMJ symptoms. Permanent neurosensory deficits were identified in five patients (five sides).