OBJECTIVE： To establish a HPLC assay for the determination of hydroxycamptothecinum and camptothecinum.METHODS： The concentrations of hydroxycamptothecinum and camptothecinum were assayed on a C18 column with a mobile phase consisting of methanol－ water(45∶ 55) at a flow rate of 1.0 ml/min,and detected at 266nm.RESULTS： The mean recovery of hydroxycamptothecinum was 100.2％ ,the 2,4,8 hours precision RSD were less than 1.8％ ;The mean recovery of camptothecinum was 99.7％ ,the 2,4,8 hours precision RSD were less than 2.0％ .CONCLUSION： The HPLC method for determination of hydroxycamptothecinum and camptothecinum was rapid,sensitive and accurate.