Here, we describe the trypanocidal and antimalarial activities from essential oils extracted from Annona vepretorum (AVOE) and Annona squamosa (ASOE) (Annonaceae) leaves. The essential oils were obtained by hydrodistillation and analyzed by gas chromatographyâmass spectrometry (GCâMS) and GCâflame ionization detection (GCâFID). A total of twenty-one compounds were identified in AVOE and twenty-three in ASOE. The sesquiterpenes are more abundant in the both essential oils. ASOE contained significant quantities of (E)-caryophyllene (27.4%), germacrene D (17.1%) and bicyclogermacrene (10.8%). The major compounds in AVOE were bicyclogermacrene (39.0%), spathulenol (14.0%) and Î±-phellandrene (11.5%). The essential oils demonstrated potent trypanocidal and antimalarial activities with values of ic50 lower than 20 Î¼g/mL, and a strong inhibition of the proliferation of amastigotes, the clinically relevant forms of Trypanosoma cruzi. In addition, through ultrastructural studies and flow cytometry analysis with trypomastigotes of T. cruzi, we identified significant ultrastructural alterations induced by the essential oils, especially in the cell membrane and mitochondria, which ultimately results in necrotic parasite death.