A case is reported of a 21 month old boy from whom a 357 g ependymona was removed. Postoperatively, radiation therapy (Co60) was administered, and the central dosage was estimated to be 4,350 r given over 46 days. Seven and a half years later craniotomy was again performed because of a supposed recurrence. However, a meningeal sarcoma weighing 370 g was found. Tumour induction by radiotherapy is discussed on the basis of published reports, and the need of estimating tumour dose in relationship to the age of the patient is stressed.