Although most pediatric tumors can be cured with lower doses of radiation than their adult counterparts, long-term radiation-induced complications and sequelae remain a major concern both in terms of frequency and intensity. Most of them have been extensively documented in the pre-chemotherapeutic era like those affecting bone, cartilage and soft tissue growth or CNS and endocrine glands. More recently the emphasis has been put on the apparent increasing incidence of reported second malignancies. This could have been favored by the chemo-radiation combinations used in most children but also has been made possible mainly by the extensive follow-up of the increasing cohort of cured children.