Blue cohosh, Caulophyllum thalictroides (L.) Michx. (Berberidaceae), is used primarily to cure menstrual disturbances and to ease childbirth. Alkaloids and saponins are considered to be responsible for its pharmacological activity. A detailed phytochemical investigation of blue cohosh resulted in the isolation of 15 compounds belonging to the alkaloids and the triterpene saponins. The structures of two alkaloids, caulophyllumines A (1) and B (2) and a saponin, cauloside H (3) both previously unknown were determined by spectroscopic techniques, including by 1- and 2-D NMR as well as by chemical analysis.