Skeletal stability was evaluated in 20 patients with mandibular hypoplasia, treated with bilateral sagittal split osteotomies to advance the mandible. Stable internal fixation was obtained using osseous miniplates and monocortical screws. Intermaxillary fixation was released after 5.15 days (range 1 to 11 days). The average B-point advancement was 6.07 mm (range 2.25 to 17.5 mm) and the average Pogonion-point advancement was 5.39 mm (range 1.75 to 14 mm). Mandibular range of motion, TMJ dysfunction and neurosensory deficits were also evaluated. The follow-up period averaged 8.85 months (range 6 to 14 months) and final evaluations were made after completion of orthodontics. Relapse measured at B-point was 10.7% and at Pogonion was 18.7%. Maximal opening decreased an average of 0.47 mm. Symptoms in 8 patients with TMJ dysfunction resolved, while 3 others developed TMJ dysfunction following surgery. Neurosensory deficits were subjectively identified in 9 patients (10 sides) and were objectively measured in 5 patients (5 sides).