Three new alkaloids, maireistemoninol (1), neotuberostemonone (2) and epoxytuberostemonone (3), together with six known alkaloids, neotuberostemoninol (4), neotuberostemonine (5), bisdehydroneotuberostemonine (6), bisdehydrotuberostemonine (7), 2-oxostenine (8), and stemotinine (9), were isolated from the roots of Stemona mairei (levl.) Krause. The structures were elucidated by a combination of 1D, 2D-NMR, and mass spectral techniques.