We have observed primary tooth enamel defects in 4 children with hemifacial microsomia. The distribution of enamel defects was concordant with the laterality of craniofacial anomalies in these patients and was most pronounced on the maxillary incisors. Since the location of enamel defects serves as a chronicle for the events of tooth formation, we propose that enamel defects may serve as a developmental marker for the events leading to hemifacial microsomia.