The major alkaloid of the leaves of Cissus rheifolia Planch. (Vitaceae) has been identified as a new quinolizidine, which has been named kayawongine and has been assigned the structure trans-2-(3,4-dimethoxyphenyl)-3-(4-methoxyphenyl)quinolizidine (2) by analysis of the spectral data. Also identified in the plant were the alkaloid cryptopleurine (1), the isomeric terpenoids vomifoliol(3) and romalea allene (4), and the major flavonoid vitexin (5). In the rural areas of northeast Thailand, the plant Cissus rheifolia Planch., or Ka-yawong, is reputed to have some medicinal value. The Thai name for the plant, which translates as "vulture without hope," derives from a local legend about the recovery of a herd of cattle from an unspecified disease after they were fed quantities of rice boiled with the roots of the plant. The waiting vultures thus lost all hope for an anticipated feast. Preliminary screening of the plant material showed a positive test for alkaloids. Because this plant belongs to the largest genus of the family Vitaceae, a family in which alkaloids have been reported but not structurally characterized, a full phytochemical investigation was initiated.