Corydalis 属植物の塩基性成分を検索する一環として、未だ研究報告がなされていない合湾産 Corydalis koidzumiana OHWI のアルカロイド成分について研究し、若干の知見を得たので報告する。Alkaloidal and neutral substances of Formosan Corydalis koidzumiana OHWI were examined. Protopine, a-allocryptopine, dl-tetrahydropalmatine, d-corydaline, d-stylopine, l-scoulerine, l-capaurine, l-isocorypalmine, l-cheilanthifoline, d-corybulbine, sanguinarine, oxysanguinarine, dihydrosanguinarine, L-(+)-reticuline, sinoacutine, pallidine, and 10nonacosanol were isolated from the whole herb of this plant.