The present study confrms the hypothesis that aristolochic acids are present in Aristolochia bridgesii. The chemical composition of aristolochic acids in this species is qualitatively similar to that of Aristolochia chilensis, with the two species differing only in the total amount of aristolochic acids present, and in the relative proportions of each aristolochic acid. These results are consistent with the fact that the two Aristolochia species in Chile both serve as host plants to Battus polydamas archidamas (Lepidoptera, Papilionidae, Troidinii).