Three new oleanane-type triterpenes, (23Z)-coumaroylhederagenin (1), (23E)-coumaroylhederagenin (2), and (3Z)-coumaroylhederagenin (3), together with two known triterpene acids, oleanolic acid and ursolic acid, have been isolated from the whole plant of Ludwigia octovalvis, and their structures have been elucidated by spectroscopic methods. All three new triterpenes showed significant cytotoxicity against two human tumor cell lines, namely, oral epidermoid carcinoma KB and colorectal carcinoma HT29, and gave IC(50) values in the range 1.2-3.6 microM.