A 1.5-year-old boy was referred to the Dutch Retinoblastoma Center with leukocoria, a white pupillary reflex. Fundoscopy revealed a white retinal tumor and ultrasonography showed a calcified mass. The patient underwent enucleation of the left eye. Histopathological examination of the retinal tumor confirmed the diagnosis 'retinoblastoma'. Leukocoria is a cardinal sign of retinoblastoma.