N-Desmethylcycleanine, a new bisbenzylisoquinoline alkaloid, and capaurine and corynoxidine, the known tetrahydroprotoberberine alkaloids, have been isolated for the first time from the rhizomes of Stephania glabra (Roxb.) Miers. The alkaloids which have been reisolated from the plant are tetrahydroprotoberberine alkaloids tetrahydropalmatine, corydalmine, stepholidine; the proaporphine alkaloids pronuciferine and stepharine; the quaternary protoberberine salts palmatine, dehydrocorydalmine, jatrorrhizine, and stepharanine; and the bisbenzylisoquinoline alkaloid cycleanine. The alkaloids of the leaves and stems of the plant were shown to be qualitatively similar by tlc. Pronuciferine hydrochloride has been found to exhibit spasmolytic activity. The biological activities of other alkaloids of the plant are reviewed. © 1982, American Chemical Society. All rights reserved.