An analysis of associated deformities in 74 patients with isolated microtia is reported. Microtia should be considered a microform of hemifacial microsomia because of similar (1) asymmetrical nature of the defects, (2) incidence and pattern of seventh nerve paresis, (3) correlation of the degree of seventh nerve weakness with grade of auricular deformity and not with the severity of mandibular hypoplasia, (4) right-sided preponderance, (5) incidence of associated cleft lip and palate, (6) male predilection, and (7) equivocal mode of inheritance. These clinical observations confirm the concept that microtia and hemifacial microsomia have the same etiopathogenesis which is not shared by mandibulofacial dysostosis.