The role of the cerebrospinal fluid lactate measurement was evaluated for the management of children with suspected bacterial meningitis. Although CSF lactate can be precisely measured, it provided no additional information over that which can be obtained from a CSF cell count. Reliance on the CSF lactate concentration alone would have increased the number of children being treated unnecessarily with antibiotics. There was neither clinical nor experimental evidence to suggest that the test should be used in the early diagnosis of meningitis. In patients with equivocal clinical and CSF findings, it failed to differentiate bacterial from nonbacterial infection. The data do not support the view that the measurement of CSF lactate has significant role in the management of children with suspected meningitis.