A highly sensitive and fast reversed-phase liquid chromatographic (LC) method combined with pulsed electrochemical detection (PED) was developed for the direct quantification of the aminoglycoside antibiotic amikacin in cerebrospinal fluid (CSF). The limit of quantification obtained was 0.06 microg/ml and linearity was established over the concentration range 0.06-4.00 microg/ml. The recovery was found to be close to 100%. This method was developed in order to study CSF pharmacokinetics of amikacin in neonates. The narrow therapeutic range calls for monitoring to ensure optimal therapy and to minimize the risk of toxic side effects such as nephro- and ototoxicity, especially in populations like preterm neonates at birth, where the predictability of amikacin clearance is limited. Typical problems to be solved were the low amikacin concentrations and the limited sample volume of CSF.