An　on-line　sample　stacking　method,　namely　field-amplified　sample　injection,　has　been　developed　for　the　separation　and　determination　of　carnosine,　anserine,　and　homocarnosine　by　capillary　electrophoresis.　Using　electrokinetic　injection,　about　130-　to　160-fold　improvement　of　sensitivity　was　achieved　without　loss　of　separation　efficiency　when　compared　to　conventional　sample　injection.　For　conventional　injection,　the　samples　were　dissolved　in　running　buffer　and　then　hydrodynamically　injected　for　10　s　(3.45　kPa).　Various　parameters　affecting　separation　and　sample　stacking　were　optimized.　Under　optimum　conditions,　linear　responses　were　obtained　over　two　orders　of　magnitude　and　the　detection　limits　(defined　as　S/N　=　3　of　carnosine,　anserine,　and　homocarnosine　were　1.5　×　10-8　to　1.6　×　10-8　mol/L.　©　2006　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.