Serum and ventricular fluid pharmacokinetic data for amikacin were evaluated prospectively in 10 hydrocephalic children with suspected ventriculitis. After the fourth or fifth intravenous 7.5-mg/kg dose of amikacin given every 8 h, mean peak serum levels were 24.3 +/- 3.2 microgram/ml (achieved at 0.5 h) with a calculated half-life of 2.2 +/- 1.1 h. Mean peak ventricular fluid levels in five patients with bacterial infection were 6.1 +/- 2.0 microgram/ml (achieved at 3 h). In the remaining five patients without bacterial ventriculitis, very low levels (less than or equal to 0.7 microgram/ml) of amikacin were detected. Ventricular fluid pleocytosis was directly correlated and glucose levels were inversely correlated with penetration of amikacin. Systemic therapy with amikacin may be the treatment of choice for children with ventriculitis meningitis caused by bacteria which are highly susceptible to this drug, thereby permitting the avoidance of the potentially hazardous intraventricular route of administration.