In the present study the problem of mandibular anterior crowding was investigated by comparing a group of adults having approximately ideal occlusion (n = 27) with a group with corresponding occlusion except for a slight crowding in the mandibular anterior segment (n = 39). Both sexes were represented. A statistical evaluation revealed that in the latter group the mesiodistal diameter of the four mandibular incisor teeth was significantly greater, whereas the intercanine width and the frequency of third molars were the same in both groups. A comparison of the craniofacial morphology of the two groups displayed limited differences, and only the basal sagittal jaw relationship and the mandibular inclination differed significantly. No significant correlations were observed between the space conditions and any of the variables studied.