Retinoblastoma patients and their relatives appear to have an increased risk of other cancers, especially melanoma, which represents 7% of second primaries in retinoblastoma survivors. Individuals belonging to families with the atypical mole syndrome (another family cancer syndrome with a genetic susceptibility to melanoma) have a recognizable phenotype, with many atypical melanocytic naevi. We report two families in which both retinoblastoma and melanoma occurred. It is of interest that in these families atypical melanocytic naevi were also demonstrated.