A new pentacyclic triterpenoid, 3,25-epoxy-3,22,23-trihydroxy-olean-12-en-28-oic acid (1), together with seven known compounds, including five triterpenoids, -amyrin (2), lantadene B (3), lantanilic acid (4), lantanolic acid (5) and ursolic acid (6) in addition to -sitosterol (7) and benzoic acid (8) has been isolated from the leaves of Lantana montevidensis. Their chemical structures were elucidated by spectroscopic analysis and by comparison with the literature data and/or authentic samples. Compound 1 showed moderate to weak antibacterial activity against Staphylococcus aureus and Escherichia coli.