The genus Aspergillus includes filamentary fungi that can cause diseases in humans and animals, being the most common forms of allergic bronchopulmonary aspergillosis, pulmonary aspergilloma and invasive aspergillosis. Furthermore, A. flavus can contaminate foods of plant origin and produce toxic metabolites to humans and animals such as aflatoxins. This research aims to study the antifungal potential of the essential oil from leaves of Cinnamomum zeylanicum and its major compound, eugenol, on Aspergillus flavus. Results showed that the essential oil showed 650 mu g/mL MIC and 2600 mu g/mL MFC, the eugenol in turn, presented 337.5 mu g/mL MIC and 1350 mu g/mL MFC. In evaluating the effect of oil and eugenol on conidial germination at all concentrations tested, the oil and eugenol inhibited the germination of fungal structures. In relation to the effects of the essential oil and eugenol on the morphology of A. flavus, it was clearly observed a reduction in hyphae pigmentation, number of conidiophores and inhibition of the conidiation process, which is the formation of conidia on the conidiophore head. Given these results, the essential oil of C. zeylanicum has great potential as possible alternative in the treatment of aspergillosis caused by A. flavus.