Résumé : A report is presented of the clinical history of a girl who at the age of 1 1/2 yr had been irradiated for a retinoblastoma of the left eye, and who 7 yr later developed fibrosarcoma of the left upper jaw. This tumor, which was etiologically attributed to the earlier irradiation, was operated on twice, without success. A massive, inoperable recurrence was treated for 2 mth by multiple systemic chemotherapy. This was followed by stabilization and later, by a distinct regression of the tumor.