The authors described anomalous development of maxillary lateral incisor non-yet published in stomatologic literature. Diagnostics and clinical findings of the anomaly and the prognosis of the affected tooth they based on the description of six longitudinal observed patients. The principal symptom of the anomaly is the disturbance of time-plan of the tooth development. Terms of the tooth mineralization, the time of eruption and root completion cannot be included either in deciduous or in permanent dentition. The tooth is the only product of the dental lamina; it has no predecessor or successor. Frequent disturbances of the eruption pathway result often in anomalous position of the tooth. Taking into consideration the fact that the anomaly appeared always in connection with hypodontia syndrome, it is possible to consider it to be the symptom of hypodontia syndrome. This fact is more significant as it enables to establish the diagnosis of hypodontia syndrome already in early deciduous dentition.