Thirty-one alkaloids have been isolated from the leaves and from the stem bark of Alstonia angustifolia from Malaysia. Twenty of them were known compounds: yohimbine, O-acetyl yohimbine, pleiocarpamine, fluorocarpamine, cathafoline, cabucraline, N-1 desmethylquaternine, vincamajine, normacusine B, lochnerine, affinisine, akuammicine, 11-methoxyakuammicine, antirhine, alstonisine, alstonerine, alstophylline, macralstonine, villalstonine and tetrahydrocantleyine. Among the 11 novel alkaloids, three were monomers: 19,20-dehydro-10-methoxytalcarpine, 19,20-dehydro-O-acetyl yohimbine and hydroxystrictamine, and eight were dimers: villalstonine N-4′-oxide, 10-methoxy villalstonine, 10-methoxyvillalstonine N-4′-oxide, 10-methoxymacrocarpamine, 10-methoxymacrocarpamine N-4′-oxide, angusticraline, alstocraline and foliacraline. Structural elucidation of the new alkaloids was based on spectral data analysis including high field 1H and 13CNMR. © 1988.