Two triterpenoids were isolated from the roots of Peganum nigellastrum Bunge. Their structures were elucidated as 3alpha-acetoxy-27-trans-caffeoyloxyolean-12-en-28-oic acid methyl ester (1) and 3-oxotirucalla-7, 24-dien-21-oic acid (2) on the basis of spectroscopic evidence. 1 is a new triterpene ester and 2 is a known compound isolated for the first time from genus Peganum.