A retrospective study of 28 patients treated by bilateral sagittal split ramus osteotomies for mandibular advancement and stabilized by two different methods of fixation was performed. Fourteen patients received rigid fixation, and 14 patients had inferior border wiring with anterior skeletal fixation. The postoperative and long-term cephalograms (greater than 6 months) were analyzed in a horizontal and vertical direction for relapse. In the horizontal direction, the rigid group experienced a 1.5% relalpse in point B and a 3.2% relapse in pogonion, while the wire osteosynthesis group had a 26.8% relapse in point B and a 34% relapse in pogonion. In the vertical direction, the rigid group experienced a 4% relapse in point B and a 9% relapse in pogonion, while the wire osteosynthesis group had a 13% relapse in point B and a 6 % relapse in pogonion. These results support the belief that rigid fixation is more stable than is wire osteosynthesis and the it helps prevent relapse in the long-term results.