The bioassay-guided phytochemical investigation of the leaf extract of Serjania yucatanensis, a woody climbing plant endemic to the Yucatan peninsula, led to the identification of a mixture of a triterpene [lup-20(29)-en-3-one] and an oxygenated sesquiterpene (beta-caryophyllene oxide), as that responsible for the originally detected trypanocidal activity in the organic crude extract. Results showed that the mixture of lup-20(29)-en-3-one and beta-caryophyllene oxide is active against trypomastigotes of Trypanosoma cruzi (IC50 = 80.3 mu g/mL) and inhibits the egress of trypomastigotes from infected Vero cells (when tested at 100 mu g/mL) without being cytotoxic.