MECC separation of 11 coumarins has been achieved by use of a running electrolyte at pH 10.4 prepared from 50 mM boric acid, 10 mM sodium tetraborate and 100 mM sodium hydroxide. The buffer solution contained 50 mM SDS and, as organic modifier 1%n-propanol. The applied voltage was 25 kV and the temperature of the capillary was kept constant at 20°C. HPLC baseline separation of the coumarin mixture was obtained by use of a reversed-phase column and an acetonitrile-water solvent gradient. UV detection was performed at 205 nm. Peak assignment and purity control were achieved by HPLC-mass spectrometry with either an electrospray interface or an atmospheric-pressure chemical-ionization interface. Compounds were detected in either negative- or positive-ion modes. These MECC and HPLC-MS methods are suitable for ‘fingerprint’ analysis of a number of coumarin-containing plants, e.g. Fr.Ammi visnagae, Rd.Scopoliae and Rd.Imperatoriae.