Perhexiline is an effective drug for angina pectoris,but prolong use of the drug may induce toxicity.A simple and sensitive method was developed for monitoring the drug to prevent from over medication.The method is based on derivatizing perhexiline with a fluorescent reagent (2-napththoxy) acetyl chloride as shown in Figure 1.The resulting derivative is highly responsive to a fluorimetric detector (λex=230 nm,λem=347 nm).The lower quantitation limit of the method is attainable at 0.3 μM with a detection limit of about 30 nM (S/N=3 with 10 μL injected).The method was applicable to the analysis of perhexiline in spiked plasma.