A previously healthy 3-month-old girl presented with symptoms of meningitis, diarrhoea, vomiting and fever. Green monkey kidney (GMK) cells inoculated with cerebrospinal fluid (CSF) revealed reovirus-like particles by electron microscopy. RNA-gel electrophoresis, immunofluorescence and virus neutralization identified the pathogen isolated from CSF as reovirus type 1. Antibody determination by immunofluorescence of paired sera showed a significant antibody titre rise to the CSF isolate and neutralization test revealed a greater than 4-fold antibody titre rise to the CSF isolate. The CSF isolate was also neutralized by reovirus type 1 antibodies. This report represents one of a few associating reovirus with CNS symptoms in humans.