Eight alkaloids have been isolated from the root bark of Crioceras dipladeniiflorus. Five of them are new: Δ14-vincamine (I) epi-16 Δ14-vincamine (II) 12-methoxy-δ 14-vincamine (V) apo Δ14- vincamine (VI), and ditabersonine (VII), a dimeric alkaloid; the three others are known, voaphylline (III), tabersonine, (IV), and vobtusine (VIII). © 1973.