This chapter discusses the occurrence and chemistry of Alstonia alkaloids. Alstonine occurs in the roots of Vinca rosea L. and the root bark of RauwolJa vomitoria Afzel. The bark of Alstonia scholaris R. Br. has long been known to contain echitamine (I) and echitamidine (II); a recent investigation of the leaves of this species has revealed the presence of picrinine. The bark of A. macrophylla Wall. contains, in addition to the five known alkaloids (villalstonine, macralstonine, macralstonidine, macrophylline, and Alkaloid M), a new tertiary base, alstophylline, C22H26N2O3, and a quaternary alkaloid, macrosalhine. The only other Alstonia species to have been examined recently is A. venenata R. Br. The bark of A. venenata contains reserpine, venenatine (12), 3-isovenenatine (alstovenine) (12, 13), venoxidine (venenatine Nb-oxide) (14), kopsinine (IV) (14,15), venalstonine (V),venalstonidine (venalstonine 6,7-epoxide), and echitovenine (VI) (16). © 1970, Academic Press, Inc.