Abstract: Objective To introduce a new method using a second-derivative ultraviolet(UV)spectrometry to determine warfarin in human urine and plasma.Methods The drug-containing samples,after mixing with methanol acetate buffer,were directly applied to the cartridges and eluted with chloroform.The eluate was strip-extracted with NaOH solution.The stripping solution was subjected to UV analysis with the absorption peak at 328nm in the second-derivative spectr a.Results The detection limits were 0.5-1.0μg·ml^-1 forurine and 2-4μg·ml^-1 for plasma,respectively.Conclusion This method can be used in the detection of big-dosage poision and trace drug content in blood.