The case of five-year old boy is reported who at the age of 18 months had successfully been operated upon for neuroblastoma and who had subsequently signs of cerebellar encephalopathy. The paraneoplastic conditions of childhood are discussed in connection with the reported case. Opsoclonus was not observed in the patient, and symptoms showed rapid improvement on methotrexate, carmustine and CCNU treatment. Six months later the child was free of neurological disturbances and only displayed a slight mental retardation (IQ: 88). Cytological alterations observed in the CSF during the cerebellar encephalopathy are described in detail. At present, 41 months after the operation the child is well and free of symptoms.