Chemical investigation of the leaves of Rauwolfia sumatrana JACK. collected in Thailand resulted in the isolation of three new indole alkaloids, 11-methoxystrictamine (1), rausutrine (4) and rausutranine (7), along with ten known bases, harman, tetraphyllicine, flexicorine, lanceomigine, perakine, β-carboline, peraksine, 10-hydroxystrictamine, cabufiline and compactinervine. The genus Rauwolfia, belonging to the family Apocynaceae, has been used as a medicinal plant to relieve many ills such as painful bowel complaints, and also as a tranquilizer and a hypotensive agent. Rauwolfia sumatrana JACK, is believed to be a general antidote to poison in Indonesia and a decoction of the bark is taken to relieve malaria in the Philippines. The plants are well known to contain monoterpenoid indole alkaloids. We investigated the alkaloidal constituents of this plant native to Thailand. The ethanol extract of the leaves of Rauwolfia sumatrana JACK., collected in Thailand (the first collection, in February 1989) gave 26.96 g of crude alkaloids. A new alkaloid, 11-methoxystrictamine (1), together with six known bases, harman, tetraphyllicine, flexicorine (5), lanceomigine, perakine, and β-carboline, was separated from the crude alkaloid by a combination of column chromatography and preparative TLC. Three new bases, i.e., 11-methoxystrictamine (1), rausutrine (4) and rausutranine (7) as well as the five known bases, harman, peraksine, 10-hydroxystrictamine (3), cabufiline (6), and compactinervine were obtained from a second collection of leaves of the same plant in April 1993. The structures of the known bases were identified by direct comparison of the spectroscopic data and the behavior on TLC in several solvent systems with those of authentic samples. Rausutrine (4) and rausutranine (7) are novel bis-indole alkaloids composed of an akuammilane unit and a vincorane unit, the latter of which has a unique iminoquinone function. The novel bis-indole alkaloids, rausutrine (4) and rausutranine (7) consisted of a vincorane-type unit, which was oxidized to an iminoquinone moiety, and an akuammilane-type unit. This is the first report of this type of dimeric indole alkaloid.