The transverse dentofacial structure of 34 young adult males with unilateral cleft lip and palate, studied by means of posteroanterior cephalograms, was compared to that of a normal sample of 102 young adult males. All cleft patients had been treated surgically and orthodontically in accordance with a standardized protocol. Orthognathic surgical treatment was carried out when growth had ended in a few subjects. In studying the posteroanterior cephalograms, eight lengths, 10 ratios, and three angular variables were used. Comparison of the cephalometric values of the subjects with cleft palate and the normal sample of young adult males indicated (1) the absence of any significant differences in angular variables describing the transverse dentoalveolar relationships in the maxillary and mandibular incisal regions as well as the mandibular position; (2) the absence of any significant differences in the ratios of the nasal, maxillary, and mandibular widths to the interorbital width; (3) the presence, in the cleft group of significantly decreased ratios of maxillary intermolar width to interorbital width, mandibular intermolar width to interorbital width, maxillary intermolar width to mandibular intermolar width, and maxillary intermolar width to maxillary width; (4) the presence, in the cleft group, of a significantly increased ratio of innerorbital width to interorbital width; and (5) significant correlations between the maxillary and mandibular molar widths in the cleft group.