Laboratory criteria used for presumptive diagnosis of enteroviral meningitis were evaluated as predictors of cerebrospinal fluid (CSF) infection. Records were retrospectively analysed of infants under four months of age admitted to hospital between 1977 and 1987 with viral CSF cultures: those with enteroviruses isolated from CSF (group 1) were compared with those with enteroviruses isolated only from non-CSF sites (group 2). Predictive value computations demonstrated that no single or combined non-CSF culture accurately predicted isolation of enteroviruses from the CSF. These results suggest that CSF viral culture is imperative in establishing the diagnosis of enteroviral meningitis in young infants.