Canescine or 11-Desmethoxyreserpine, a new alkaloid isolated by Stoll and Hofmann from Rauwolfia canescens has been submitted to a comparative pharmacological study with Reserpine. The circulatory effects obtained with these two alkaloids can practically not be distinguished from each other. Like Reserpine also Canescine exhibits a sedative action and produces pupillary constriction. © 1955 Birkhäuser Verlag.