Abstract: From the root of Aristolochia contorta Bunge six chemical constituents were isolated; one of them is a new phenanthrene compound containing nitro group for which the name aristolochic acid E is suggested. By means of spectral methods combined with chemical analysis the chemical structure of aristolochic acid E was determined to be 7-methoxy-8-hydroxy-aristolochic acid. The other components were identified as allantoin, aristolochic acid A, magnoflorine, β-sitosterol and daucosterol respectively.