Literature has shown that, even with the conservative nontraumatic surgical techniques, early repairing surgeries induce changes in the upper dental arch morphologic characteristics in patients with cleft lip and palate. The evaluation of unoperated adult cleft patients enables us to exclude the influence of treatment, emphasizing the morphologic characteristics inherent to the presence of the cleft and its functional counterbalances, that is, the morphologic pattern imposed by cleft. In this study, the maxillary dental casts of 31 unoperated adult complete bilateral cleft lip and palate patients (20 men and 11 women) were compared to a noncleft sample matched for gender. Intercanine, inter-first premolar, inter-second premolar and inter-first molar arch widths measurements as well as arch length were measured from xerox copies taken of the models. The findings indicate the presence of premaxillary prognathism and a progressive increase in the constriction of the dental arches. This constriction of the maxillary segments, even in the absence of surgical intervention, is a result of the absence of an intact palate between the two maxillary processes. Although gender significantly influenced the size of the maxillary arches in the noncleft patients, similar differences were not observed in the cleft group. It seems that the presence of the cleft in itself has the greater influence on the morphologic characteristics of the maxillary arch than gender.