The effects of radiation and chemotherapy on the developing dentition of a leukemic patient are described. Microdontia and bizarre morphology were observed in teeth developing in close proximity to the field of radiation. Teeth in more advanced stages of development were affected less severely. However, the deleterious effects of chemotherapy could not be excluded. The effect of irradiation on human adult and developing teeth has been documented widely. 1-12 However, the effect of chemotherapy is emerging only lately. Chemotherapy is a treatment modality that has been utilized more recently both as the sole treatment or in conjunction with radiotherapy. The effects of radiotherapy usually are confined to the radiation site, but the effects of chemotherapy may be more widespread because of its systemic distribution and structures and organs unrelated to the primary tumor may be affected. These. manifestations may become apparent only after a number of years. 12 The present article reports the sequelae of the aforementioned treatments implemented in a leukemic child patient.