Three novel triterpenes, 3,4-seco-olean-12-ene-3,28-dioic acid (4), 3alpha-hydroxyolean-11-en-28,13beta-olide (5), and 3alpha-hydroxyoleane-11:13(18)-dien-28-oic acid (6), were isolated from the aerial parts of the Argentinean shrub, Junellia tridens. Another five compounds-oleanolic (1), oleanonic (2), and epioleanolic acids (3), all biosynthetically related to the three new oleananes, and epibetulinic acid (7) and sitosterol (8)-were also isolated. Structures were elucidated primarily by 1D and 2D NMR and mass spectrometry, and all protons and carbons of the three novel compounds were fully assigned by NMR. We report the minimum inhibitory concentrations of these compounds against Mycobacterium tuberculosis and conclude that they are responsible for antitubercular activity originally observed in the crude plant extract. LC-MS data is provided on the occurrence of triterpenes 1-6 in six other species of Junellia.