Ching-Mu-Hsiang, root of Aristolochia debilis, Sieb.et Zucc., is one of the Chinese drugs used in hypotension therapy.From this drug the authors have succeeded in isolating three crystalline components; among which two were obtained as tiny yellow needles, m.p.275° (I) and m.p.269°(Ⅱ); the other one formed white needles, m.p.235°(Ⅲ).The last component (Ⅲ) was identified as allantoin by its mercury complex, and no melting point depression was ohserved on admixture with authentic specimen.