A method for the determination of dodine in agricultural products was developed by using liquid chromatography-electrospray ionization mass spectrometry (LC/ESI-MS). Dodine was extracted with acetonitrile and then acetonitrile-water (7 : 3) from a sample, and re-extracted with ethyl acetate. The extract was cleaned up on a PSA cartridge column (500 mg), and dodine was analyzed by LC/MS. In the case of oil seeds and nuts, hexane/acetonitrile-hydrochloric acid partition was performed to remove lipids before re-extraction with ethyl acetate. In the case of samples that contained a lot of chlorophyll, the eluate of the PSA cartridge column was further cleaned up on a graphitized carbon cartridge column (500 mg). The calibration curve was linear from 0.0001-0.02 microg/mL of dodine. The recoveries of dodine from sixteen kinds of agricultural products fortified at 0.1 mg/kg were 80.3-100.0%, and their relative standard deviations were 0.3-6.4%. The limits of detection (S/N=3) were 0.0006 mg/kg.