This study was performed to compare the soft tissue movement in facial profile predicted by a computer package with those that had actually occurred following a maxillary advancement osteotomy. The source of the material was serial lateral cephalograms for 25 conseutive patients who had received similar Le Fort I osteotomies primarily to correct an anteroposterior skeletal discrepancy. Many of the digitized points on the soft tissue profile were surprisingly well predicted by the computer package. The chin and profile changes resulting from mandibular autorotation and/or a genioplasty were generally predicted accurately. However, in some cases prediction was less consistent, particularly in the region of the nose and upper lip. In this latter group of patients, initial size, thickness, and morphology of the soft tissues appeared to be important factors to which some consideration could be given in the furtehr refinement of this type of software.