Chemical investigation of the roots of Aconitum forrestii Stapf resulted in the isolation of two novel C19-diterpenoid alkaloids, forestine (6) and foresticine (7), together with three known alkaloids, chasmanine (2), talatizamine (3), and yunaconitine (4). The structure derivation of the new alkaloids is based mainly on spectroscopic evidence and correlation of foresticine with chasmanine (2). © 1984, American Chemical Society. All rights reserved.