AIM: To present the dentofacial changes produced by mandibular body ostectomy in a female patient, 19 years of age, and the patient's 2-year follow-up records. SUBJECT AND TREATMENT: An increased lower facial height and a prominent chin, Angle Class III molar relationship, edentulous gaps in the first premolar regions of the mandible, with overjet and overbite values of -1 mm were observed. Radiographic evaluations revealed impaction of the maxillary right canine. The treatment plan included leveling and coordination of the arches, extraction of the maxillary left first premolar and the impacted canine, and a "rectangular" body ostectomy of 5 mm. RESULTS: Treatment lasted for 24 months. An increase of ANB was observed. Normal overjet and overbite were established. The posterior movement of the lower lip and soft and hard tissue points B and Pg were observed. No major changes were observed for the dentofacial structures at the 2-year follow-up visit. However, slight spacing at the ostectomy sites was present. CONCLUSION: The rectangular mandibular body ostectomy might be considered an alternative effective method for the correction of mandibular prognathism, particularly when the posterior occlusion is to remain unchanged and when edentulous gaps in the anterior region of the mandible are present.