The chemical composition of commercial , , and essential oils as well as their antifungal activity against four pathogenic fungi isolated from Mediterranean rice grains has been investigated. Eighty nine compounds accounting for between 98.5 and 99.4% of the total essential oil were identified. The phenylpropanoids eugenol (89.37 ± 0.29%) and eugenol (56.34 ± 0.41%), followed by eugenol acetate (19.48 ± 0.13%) were, respectively, the main compounds in clove and cinnamon essential oils, whereas large amounts of the oxygenated monoterpenes 1,8-cineole (58.07 ± 0.83%) and α-terpinyl acetate (13.05 ± 0.44%) were found in bay leaf essential oil. Clove and cinnamon oils showed the best antifungal activity results against all tested fungi. Against , clove essential oil displayed the best antifungal effect, whereas against , cinnamon essential oil was more active. Both essential oils showed a similar antifungal effect towards and . In vitro studies in inoculated rice grains showed that clove and cinnamon totally inhibited pathogenic fungal development after 30 days of incubation. In vivo studies showed that eugenol used with a polysaccharide such as agar-agar formed a fine coat which wraps the inoculated rice grains, creating a natural biofilm and reducing the development of all pathogenic fungi (80-95%) for 30 days.