(+)-Tetrahydrocantleyine, (-)-cantleyine, (-)-akuammicine, pleiocarpamine, echitamidine, 20-epi-19 & xi;-echitamidine, echitamine, nor-echitamine and undulifoline, a new alkaloid with the rare uleine skeleton, have been isolated from the stem bark of Alstonia undulifolia. The structures were established by spectroscopic means. © 1992.