The normal cranio-facial skeleton may demonstrate varying degrees of asymmetry, ranging from sub-clinical asymmetry compatible with normal dental occlusion to gross asymmetry arising from traumatic, pathological or developmental causes. An intermediate group has clinical cranio-facial asymmetry associated with dental malocclusion but with no apparent pathological cause. There may be compensatory development of the dento-alveolar structures which reduces the effect of the skeletal asymmetry on the dental occlusion. Radiographic analysis of the location of the asymmetry is unsatisfactory but some individuals in the intermediate group show curvature or distortion of the skull base which can be demonstrated although not quantified on SMV x-rays. Skull deformation can arise in utero, during birth or in infancy. One form of skull and facial obliquity (plagiocephaly) can occur a few weeks after birth in infants who were symmetrical at birth. There may be associated asymmetry of the axial skeleton and plagiocephaly was a constant feature in one survey of infantile scoliosis. An association exists between facial asymmetry, skull base asymmetry, plagiocephaly and asymmetry of the axial skeleton.