This study includes all cases of retinoblastoma reported in Sweden between 1958 and 1971. The incidence of the disease was 1 per 18 000 live births. Only in six cases was there a familial history and five of these cases were bilateral. The tumour was bilateral in 37.5% of all cases. All cases with unilateral tumour had been treated with enucleation. In the bilateral cases one eye had also been enucleated and the other eye treated by local irradiation therapy. Tumour invasion into choroid was found in 29% and into the optic nerve on 11% of the cases. The mortality was only 4.5%.