Nine patients aged between 18 and 35 years who had severe skeletal Class III malocclusion and moderate-to-severe mandibular asymmetry, were assessed by a non-invasive, landmark-based, three-dimensional system before and after mandibular reduction by sagittal split osteotomy and LeFort I maxillary advancement. The three-dimensional coordinates of 50 facial soft tissue landmarks were collected, and a series of anthropometric measurements was calculated and compared with reference values from 240 healthy subjects of similar sex, age, and ethnic group. Patients were more asymmetrical than normal subjects before the operations, particularly in the gonion. Postoperatively, total and lateral asymmetry was considerably reduced. The three-dimensional approach was a valuable complementary diagnostic aid that enabled quantitative evaluation of the final soft-tissue results without invasive procedures.