Six patients with meningitis due to retinoblastoma are described. The diagnosis may be suspected on clinical examination but is made by the demonstration of malignant cells in the CSF. These patients have been treated with cranial irradiation together with systemic and intrathecal cytotoxic drugs. There is one survivor. It is suggested that the CSF should be examined in all cases at risk so that the appropriate treatment can be started promptly and thus improve the prognosis.