the daily consumption of natural antioxidants protects against oxidative damage caused by reactive oxygen species (ros), including dna damage, and can reduce the risk of cancer, atherosclerosis and other degenerative diseases. the pulp of pequi (caryocar brasiliense camb.) fruit, a tree native to the brazilian savannah, contains several compounds with antioxidant properties, including carotenoids, vitamin c, phenolic compounds such as flavonoids, saponins and tannins, and essential oils. in this work, we examined the ability of organic and aqueous extracts of pequi fruit pulp to protect against the genotoxicity induced by two antineoplastic drugs, cyclophosphamide (cp) and bleomycin (blm). micronucleus tests with mouse bone marrow cells and single-cell gel electrophoresis (comet assay) with peripheral blood leukocytes were used to examine the effects of cp and blm, respectively. the antioxidant activity of the extracts was assessed by measuring lipid peroxidation with the tbars method in mouse plasma. the fruit pulp extracts had no clastogenic or genotoxic effects in the cells studied, but both extracts protected against oxidative dna damage caused by blm or cp, indicating an ability to inhibit chemical mutagenesis in vivo. however, the protective effect against oxidative dna damage depended on the dose of extract used. at the doses tested, the aqueous extract enhanced lipid peroxidation in mice of both sexes, especially in males. in contrast, the organic extract enhanced lipid peroxidation only in male mice, with no significant effect in females. these results suggest that, with adequate adjustment of the dose, an organic extract of pequi fruit pulp could be a useful dietary supplement with natural antioxidant activity, at least in females.