A continuing study of Catharantbus Lanceus leaf alkaloids for antineoplastic compounds has led to the isolation of tetrahydroalstonine, lochnerinine, and a new alkaloid, periformyline. Details concerning the isolation of these alkaloids and the structure elucidation of periformyline, the first example of an Nb‐substituted formyl indole alkaloid to be found in nature, are presented. Copyright © 1965 Wiley‐Liss, Inc., A Wiley Company