PURPOSE: For a minor degree of mandibular prognathism, mandibular anterior segmental osteotomy (ASO), usually extracting the bilateral premolars, has been performed frequently to correct malocclusion of the anterior teeth. Preoperative planning using cephalometry and a dental model is very important for such a orthognathic surgery. Depending on the specific preoperative mock surgery with the dental model, ASO, with ipsilateral unitooth extraction, is defined to be feasible and performed for ten patients. The comparisons of its preoperative and postoperative analysis of clinical photographs, dental casts, and lateral cephalograms, for soft tissue profiles, skeletal and dental relationships are described in the following, and its clinical applications are noted. METHODS: From March 1, 2004, to March 31, 2006, We performed 10 mandibular ASO by extraction of ipsilateral unitooth to improve their lower facial profiles and the lip relationships. Patient age ranged from 19 to 33 years, with a mean age of 25.6 years. Two were males and eight were females. RESULTS: All patients were satisfied with aesthetic and occlusal changes postoperatively. Significant and persistent decrease in the SNB and interincisal angle were observed in the postoperative cephalometries. The soft tissue profiles also were improved and near Ricketts's esthetic line. Other combined procedures include nine genioplasties, two rhinoplasties, and one blepharoplasty. One patient complained of transient unilateral inferior mental nerve paresthesia. There were no other significant complications or relapses throughout the follow-up period(6-20 months). CONCLUSION: Mandibular ASO, extracting the ipsilateral unitooth, was performed for ten patients to correct mild mandibular prognathism. The amount of setback of the mandibular anterior portion was 2 to 3mm, and satisfactory results were obtained combined with genioplasties.