Two new alkaloids, 4,9-dimethoxy-l-vinyl-β-carboline (XI) and β-carbolin-l-yl 3-(4,8-dimethoxy-β-carbolin~ 1 -yl)-1 -methoxypropyl ketone (XII) were isolated from the wood of Picrasma quassioides bennet (simaroubaceae) together with known alkaloids, 1-ethyl-4-methoxy-β-carboline (VI), 4-methoxy-l-vinyl-β-carboline (VII), 4,8-dimethoxy-l-vinyl-β-carboline (VIII), canthin-6-one (IX), and 5-methoxycanthin-6-one (X). The structures of these alkaloids were elucidated on the basis of spectroscopic evidence. © 1983, The Pharmaceutical Society of Japan. All rights reserved.