A method of HPLC for the quantitative determination of acemetacin and indometacin in human serum is described. After being extracted with diethyl ether, acemetacin and indometacin were analyzed by reversed-phase HPLC(Spherisorb-C8) and UV-detector(254 nm), with tolbutamide as internal standard. The mobile phase was a mixture of V(acetate buffer solution, pH 4.6):V(methyl alcohol):V(acetonitrile) = 55:5:40 and at a rate of 1.0 mL/min. Over the mass concentration range of 12.5 micrograms/L-1.6 mg/L, both the calibration curves were linear, r = 0.9996, n = 8. The average recoveries of acemetacin and indometacin were 77.2% and 86.7% respectively. The within-day and between-day RSD of acemetacin and indometacin were less than 5% and 10% respectively.