Two new cytotoxic oxindole alkaloids, 17-demethoxy corynoxine B and 17-demethoxy-isorhynchophylline were isolated from the whole plant of Amsonia brevifolia and their structures elucidated through a combination of physical, chemical and spectroscopic methods. Several terpenoids and nine other indole alkaloids were also isolated. Because the constituents of A. brevifolia and A. tomentosa appeared to be identical qualitatively and quantitatively, it is suggested that only the name A. brevifolia be retained for this species. © 1988.