Purpose: There has been dispute about the exact factors influencing dental arch development in adult cleft palate patients, so we designed this study to investigate the effects of operative and anatomic factors on the development of dental arch morphology. Patients and Methods: A retrospective cohort study was conducted among 3 groups of patients (operated, unoperated, and normal) from West China College of Stomatology, Sichuan University, Chengdu, China. The differences in dental arch morphology, including length and width of the upper and lower dental arches, inclination of the palatal shelf, and palatal height, were analyzed by variance analysis with SPSS software, version 13.0 (IBM, Armonk, NY). Results: We enrolled 90 individuals: 30 unoperated adults with bilateral cleft lip and palate, 30 adults with operated bilateral cleft lip and palate, and 30 normal adults. The widths of all upper and posterior lower arches, lengths of the anterior upper arch, palatal height, and palatal shelf inclination in the operated group were smaller than those in the unoperated group; the lengths and widths of the anterior upper arch were smaller whereas the widths of the posterior upper and lower arches, palatal height, and palatal shelf inclination were greater in the unoperated group compared with the normal group. Conclusions: Operated cleft patients show the most severe deformation of the maxillary arch, especially in the anterior part. There is an intrinsic palatal tissue deficiency in cleft patients, whereas the maxillary arch deformation in unoperated cleft patients is limited to the anterior region only. (C) 2013 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 71:929-937, 2013