Five　flavonoids　(catechin,　hyperoside,　quercitrin,　quercetin,　and　rutin)　were　separated　and　determined　by　capillary　electrophoresis　with　electrochemical　detection.　Effects　of　several　important　factors,　such　as　the　pH　and　concentration　of　running　buffer,　separation　voltage,　injection　time,　and　detection　potential　were　investigated　to　determine　the　optimum　conditions.　The　five　flavonoids　were　baseline　separated　within　20　min　in　a　60　cm　length　capillary　at　a　separation　voltage　of　19.5　kV　with　a　running　buffer　consisting　of　60　mmoL/L　Na2B4O7-120　mmoL/L　NaH2PO4　(pH　=　8.8).　The　relationship　between　peak　current　and　analyte　concentration　was　linear　over　about　two　orders　of　magnitude　with　detection　limits　(S/N　=　3)　ranging　from　0.02　to　0.05　μg/mL　for　all　compounds.　This　method　was　successfully　used　to　determine　the　above　five　flavonoids　in　Agrimonia　pilosa　Ledeb.　with　relatively　simple　extraction　procedures,　and　the　assay　results　were　satisfactory.　©　2005　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.