The structure of hasubanonine was reexamined and the compiate constitution (IIc) including the absolute stereostructure was presented. The structure of homostephano-line was also investigated and three possible structure for this alkaloid were shown in formulae (XIIIa), (XIIIb), and (XIIIc). These two alkaloids have a novel skeleton (XII) which has not been known hitherto in the natural sources, for which the name “hasubanan” was proposed. © 1965, The Pharmaceutical Society of Japan. All rights reserved.