due to the potential of phytochemicals as therapeutic agents, there is increased interest in plant compounds with this biological activity, such as the essential oils of medicinal and aromatic plants. this study assessed the antioxidant activity of essential oils from the species croton grewioides and its major compounds (cgr106 and cgr126 - 29.51% and 42.68% of eugenol; cgr126 and cgr112 - 45.97% and 85.58% of methyl eugenol; cgr106 - 59.85% of methyl chavicol). antioxidant activities were evaluated by the systems 2,2-diphenyl-1-picryl-hydrazyl (dpph), 2,2'-azinobis (3-ethylbenzoathazoline-6-sulfonic acid) (abts), ferric reducing ability (frap) and co-oxidation of -carotene/linoleic acid. the best results were found in the essential oils cgr106 and cgr126, from c. grewioides. samples with eugenol in their composition showed greater free-radical stabilization capacity. essential oils of both accessions presented antioxidant capacity in the methods tested.