Three new natural onoceranoid triterpenes, lansionic acid (1), 3beta-hydroxyonocera-8(26),14-dien-21-one (2), and 21alpha-hydroxyonocera-8(26),14-dien-3-one (3), were isolated from the fruit peel of Lansium domesticum together with two known triterpenoids (4 and 5), and their structures were elucidated from spectral data. These triterpenoids exhibited mild toxicity against brine shrimp (Artemia salina).