Abstract:Four diterpenoid alkaloids were isolated by means of column chromatography and preparative HPLC from the roots of Aconitum leucostomum Worosch. Their structures were determined from the spectral data. One of them was found to be a new compound named leucostine ( Ⅱ ). The other three are known alkaloids, leuconine ( Ⅰ ), dehydroacosanine ( Ⅲ ) and sepaconitine (IV).