Four kindreds with family-specific malposition of cuspids were studied. Besides malposition of cuspids, the members also showed varying combinations of other anomalies: malposition, malformation or hypodontia of upper lateral incisors, second bicuspids and lower central incisors. The pedigrees provided convincing evidence for autosomal dominant transmission of the abnormalities studied. Their nature and location allow the assumption that they represent different expressions of one dominant gene causing a primary disturbance in the critical marginal area of the embryonic dental lamina.