Childhood cancer, such as that manifested by neuroblastoma and hepatoblastoma tumors, is one of the leading causes of death for young children. Chemotherapy is one of the most important approaches available, though it is considered to cause tooth developmental disturbances when patients receive treatment during that period of development. Microdontia, disturbed root development, hypodontia and enamel hypoplasia are reported to be possible late adverse effects of chemotherapy. We analyzed 3 children, for whom chemotherapy had been given for treatment of cancer from the ages of 1 to 2.5 years old. Intraoral examinations revealed microdont of the bilateral maxillary lateral incisors and canines in 1 case, whereas that of the bilateral mandibular first premolars was shown in another. Orthopantomograph examinations revealed congenital absence of the first and second premolars in all 3 cases. The developmental period of the affected teeth in these cases appeared to correspond to the chronological age when chemotherapy was administered.