Therapeutic results after beta-irradiation suggest that 106Ru/106Rh applicators have become an acceptable means of radiotherapy in patients suffering from retinoblastoma with a height of not exceeding 5 mm. Because of the rapid fall-off radiation dose it is possible to deliver a high dosage to the tumor without danger of radiogenic damage to the whole globe. Out of 22 children suffering from retinoblastoma a complete destruction and scarification of the tumor could be obtained in 18 eyes with sufficient vision acuity over a follow-up period of more than 5 years. In 4 cases an additional photocoagulation was necessary. beta-Irradiation avoids an undesirable high-volume dose. It may, therefore, be regarded as a useful contribution to radiotherapy of retinoblastoma.