Abstract: A method was developed for the determination of the novel antihypertensive drugnaftopidil in biological samples by HPLC,Metoprolol was used as the internal standard.The analyticalcolumn was a stainless steel column filled with 10 μmC₁₈ packing.The mobile phase was a mixture ofmethanol-acetonitrile-water-0.2 mol·L^-1Ac-0.2 mol·L^-1aAc(50 :45 :5:0.9:0.1).Detection was performed at UV 232 nm,Biologieal samples can be well purified after twoextractions with ether.The lowest detection limit was 5 ng· ml^-1.The precision and accuracywithin-day and day-to-day ranged from 3.17 to l0. 88%,The mean recoveries were 79.35%to95.72%,The results showed that this method was simple,sensitive and good enough to be used inpharmacokinetic study of naftopidil.