Thirty-nine patients who had been treated for mandibular prognathism by either bilateral sagittal split of transoral vertical ramus osteotomy were evaluated for skeletal shifts postsurgery. Using lateral cephalograms taken before surgery, immediately after surgery, and at least six months postsurgery, surgical and postsurgical changes were evaluated using linear, angular, and point coordinate measurements. The postsurgical increase in the SNB angle and the anterior movement of B point, pogonion, and menton during the postsurgical period were statistically significant in the bilateral sagittal split group but not in the transoral vertical ramus osteotomy patients.