This report deals with the results of a study that was made on the passage of fosfomycin into the CSF in 22 children with meningitis (11 parotideal meningitis and 11 meningococcal meningitis). The plasma and liquor levels of fosfomycin were determined in the acute phase of the illness and after the normalization of the CSF, with the object of studying the passage of the antibiotic through the blood-brain barrier in the presence and absence of meningeal inflammation. A greater permeability of the meninges was found to exist when they were in an inflammatory state and there seems to be a certain accumulative effect in the CSF when the fosfomycin is administered by intravenous perfusion. The concentrations that were obtained in the CSF were not high enough to justify the exclusive use of fosfomycin in the treatment of meningitis. Nevertheless, considering its wide antibacterial spectrum, its MIC against different microbial species and its lack of toxicity, we believe that fosfomycin can be of use when associated with other antibiotics in the treatment of meningitis caused by S. aureus, D. pneumoniae, H. influenzae, E. coli, P. mirabillis and S. marcescens.