Rhizophora mangle L. is a plant species traditionally used in the culture of the Espirito Santo State in the making of clay pots. Previous studies with aqueous extract of leaves from R. mangle L. demonstrated satisfactory antibacterial and antiulcer activities1. The pathogenesis of various gastrointestinal diseases, including ulcers, is in part due to oxidative stress produced by reactive oxygen species (ROS). ROS plays double role in organisms, having deleterious and beneficial effects. The beneficial effects usually occur in low concentrations, while an overproduction of these reactive species can generate the oxidative stress, which is interconnected to inflammatory processes, ulcers and others pathologic process2. The objective of this study is to evaluate the antioxidant activity of ethanolics extracts of leaves and barks from R. mangle L. against the inhibition of hydroxyl radicals, superoxide anion and hydrogen peroxide. The ethanolics extracts of barks and leaves were prepared by maceration and the phytochemical characterization was obtained according to the literature3. The antioxidant activity was evaluated through the hydroxyl radical, hydrogen peroxide and superoxide anion capture assays by spectrophotometric methods4. The assays were performed in triplicate, repeated at least three times, the trolox was used as standard and the results were expressed as percent inhibition. The phytochemical characterization of the barks and leaves confirmed the presence of flavonoids, coumarins, tannins, polyphenols, triterpenes and sterols. The barks extract had significant superoxide anion capture activity, presenting 86.09% in 100 μg/mL and for hydroxyl radical assay, presented inhibition of 97.07% in the same concentration. In both assays the statistical analysis showed significant difference with superior results for the barks extract. For the hydrogen peroxide capture assay, the percentage of inhibition were 36.16% in the concentrations of 100 μg/mL, while trolox in the same showed percentages of inhibition higher than 70%. Leaves extract didn’t show significant activity on any of the assays. In the superoxide anion and hydrogen peroxide capture assay the leaves extracts presented 47.49% and 42.74% of inhibition, at concentrations of 100 μg/mL, respectively, but against the hydroxyl radical there wasn’t activity. The results show that barks extract presented excellent antioxidant activity against the radical hydroxyl and superoxide anion, but low capacity of inhibition of the hydrogen peroxide radical, while the leaves did not show good activity in these assays. However, it still is necessary to complement the study to prove its biological potential.