Neglected diseases like leishmaniasis and trypanosomiasis still remain a serious Public Health problem throughout the world with severe socio-economic impacts. There is an urge for new therapeutic alternatives and Annona essential oils have showed to be active against some of their protozoan agents, therefore encouraging this study. The volatile oil from the leaves of A. crassiflora (Mart.) (Annonaceae) was isolated (0.06% w/ w) in a Clevenger-type apparatus and analysed by GC-MS and GC-FID. Among the 41 identified compounds (83.2 %), sesquiterpenes were predominant (81.7 %), followed by monoterpenes (0.8 %) and other metabolites. The major constituents were α-amorphene (43.6 %), E-caryophyllene (17.7 %) and germacrene (5.3 %). The antiprotozoal activity was evaluated against four Leishmania species and T. cruzi, determining the parasites viability by MTT assay. The oil was mostly active in the promastigotes of L. (L.) infantum chagasi (IC50: 25.97 μg/ mL), while the activity against T.cruzi trypomastigotes (IC50: 5.31 μg/ ml) was nine folds higher than benznidazole and more active than those of the other Annona species. These results give support for a further study on the antiprotozoal compounds of A.crassiflora.