The 80% ethanol extract of Alstonia yunnanensis afforded five new monoterpenoid indole alkaloids: 11-hydroxy-6,7-epoxy-8-oxo-vincadifformine (1), 14-chloro-15-hydroxy- vincadifformine (2), perakine N(4)-oxide (3), raucaffrinoline N(4)-oxide (4), and vinorine N(1),N(4)-dioxide (5), together with