[Show abstract][Hide abstract] ABSTRACT: The determination of amphetamine in rat's blood and brain simultaneously by micordiaysis technique and HPLC/fluorescence derivatization is described. Microdiaysis is used to sample rat's blood and brain fluid and the amphetamine content is evaluated by HPLC/fluorescence derivatization assay. Dansyl chloride is used as fluorescence derivatization reagent. The detection limit, linearity and precision associated with this assay were evaluated. Pharmarcokinetic parameters of amphetamine in rat's blood and brain are also reported.