Limited data are available about cefixime pharmacokinetics and cerebrospinal fluid (CSF) penetration in infants and young children. Ten patients with bacterial meningitis and 8 undergoing CSF shunt placement, aged 2-22 months (mean 9.5 ± 6.5 months), were given a single dose of cefixime suspension, 8 mg/kg, before undergoing a routine lumbar puncture. Patients were fasted for 2 h before and 2 h after drug administration. Blood samples were collected just before drug administration (0 h) and at 1,2, 3, 4, 6, 8 h; CSF was obtained at 1-8.8 h after drug administration. Cefixime was measured by a high-performance liquid chromatographic method. The peak scrum concentration of cefixime ranged from 0.85 to 6.2 (mean 3.1) μg/ml and occurred at 2-8 h (mean 4.5). The area under the serum concentration-time curve ranged from 5.3 to 28.4 ug h/ml, and the elimination half-life ranged from 2.6 to 5.6 h. CSF concentrations ranged from 0.02 to 0.57 μg/ml. The mean CSF concentration of cefixime was 0.22 μg/ml in patients with meningitis and 0.10 ug/ml in those undergoing shunt placement (p < 0.02). The mean CSF concentration/serum concentration ratio was 11.7 in patients with meningitis compared with 5.4 in those undergoing shunt procedures (p < 0.02). These data indicate that cefixime can be considered as an alternative to other antimicrobials for infants and children with respiratory and urinary tract infections, since the observed peak serum concentration exceeded the minimum inhibitory concentrations of the common pathogens by severalfold. Cefixime should not be used for the treatment of bacterial meningitis, since the achievable CSF concentrations will most likely not exceed the minimum bactericidal concentration of common pathogens by 10-f