The chemical composition of the essential oils from Brazilian species of the genusAristolochiaare being reported for the first time. The oils, which were obtained by steam distillation from seven BrazilianAristolochiaspecies:A. gigantea, A. macroura, A. cymhifera, A. rodriguesia, A. birostris, A. papillarisand A.triangularis, were analyzed by GC/MS and found to be rich in sesquiterpenes. The major components of the various oils were:—A. birostris:β-caryophyllene (13.9%), α-humulene (16.4%) and germacrene A (13.3%);A. cymhifera:n-undecane (17.7%) and dodecane (12.4%);A. gigantea:β-caryophyllene (8.8–19.3%), germacrene D (16.3–24.9%), γ-elemene (0–21.6%), trans-α-bergamotene (2.3–12.5%), (E)-nerolidol (0–23.4%), linalool (0–14.6%), nerol (0–11.5%) and geraniol (0–26.2%); A.macroura:δ-elemene (1.2–12.4%), α-copaene (2.5–13.3%), β-caryophyllene (10.6–15.3%), α-humulene (15.5–20.5%), γ-elemene (10.4–11.6%) and (E)-nerolidol (0–33.1%), farnesene (12.7%); A.papillaris:calarene (13.6%), α-humulene (17.7%), γ-cadinene (10.9%) and δ-cadinene (10.6%); A.rodriguesia:α-copaene (12.4%), β-bourbonene (11.9%) and β-elemene (10.7%); A.triangularis:(E)-nerolidol (12.3%) and decane (11.8%).