Two new alkaloids from Rauwolfia canescens, pseudoreserpine and raunescine have been studied for pharmacologic activity in mice and dogs. Both pseudoreserpine and raunescine have reserpine-like activity, but are less potent than reserpine. The reduction in potency has been attributed to the substitution of the methoxyl group on C-17 in ring E by a hydroxyl group. © 1957, SAGE Publications. All rights reserved.