Two minor alkaloids were newly isolated from Uncaria rhynchophylla Miq., And their structures elucidated as geissoschizine methyl ether (a new compound) and akuammigine, respectively. The Cotton effect due to the chirality of the E ring of heteroyohimbinoid alkaloids was studied by using some model compounds. The conformation of akuammigine was also studied. © 1977, The Pharmaceutical Society of Japan. All rights reserved.