A simple, highly sensitive and selective method is described for adamantanamine determination in plasma and urine by high-performance liquid chromatography with fluorescence detection. The method involved a simultaneous extraction and derivatization of biological fluids with a 9-fluoreneacetate (9-FA) solid-phase derivatization reagent. This approach eliminated tedious sample preparation steps and provided automatic derivatization with selective and efficient sample clean-up for direct injection of biological fluids. Derivatized adamantanamine was separated under conventional reversed-phase conditions and determined by fluorescence detection. The optimization and validation of the derivatization method with the 9-FA solid-phase reagent is described.