OBJECTIVE To establish a method for determining the concentration of doxofylline in plasma. METHODS Plasma sample was used for the chromatography after protein precipitation and centrifuging on the basis of internal standard method, the μBondapak C₁₈ column was used. Methanol-water (38∶62)(V/V) was used as mobile phase, and caffeine was used as internal standard, with the flow rate of 1.0 ml·min^-1.The detection was carried out at 275 nm. The temperature of column was at room temperatur.RESULTS The separation and determination of the sample and internal standard could be accomplished preferably. The calibration curves were linear in the range of 0.5～16.0 μg·ml^-1 for doxofylline .The average recoveries of doxofylline were 99.9%(RSD=0.15%，n=5). CONCLUSIONS This method provides a rapid and accurate way to measure the concentration of doxofylline in plasma.