A new alkaloid, (E)-3-(3-methyl-1-oxo-2-butenyl)-6-methoxy-1H-indole (1), along with two known ones, was isolated from the aerial parts of Cimicifuga heracleifolia. The structure of 1 was elucidated on the basis of extensive spectroscopic data analysis. The structures of known compounds were determined by comparison with the literature data.