This study aims to evaluate the antioxidant and cytotoxic effect of aqueous and ethanol extracts from the leaves of Tithonia diversifolia (Asteracea) on the free radical DPPH • and larvae of Artemia salina Leach, respectively. Samples of Tithonia diversifolia (Hemsl.) A. Gray was collected in the district of Fazendinha, Macapá- Amapá. The selected leaves were dried at 40C and then ground in a mill to obtain a fine-grained powder. After obtaining the aqueous and ethanolic plant extracts, they were subjected to phytochemical analysis for identification of metabolites classes. Phytochemicals tests were conducted to verify the presence of saponins, organic acids, reducing sugars, phenols, tannins, alkaloids, cyanogenic glycosides, resins, proteins and amino acids. The evaluation of the antioxidant activity was assessed by the sequestrant ability extracts on free radical DPPH • (2,2-diphenyl-1-picrylhidrazila). There was prepared a methanol solution of DPPH at the concentration of 40mg / ml. Where the aqueous and ethanolic crude extracts T. diversifolia were diluted in methanol at the following concentrations (5-2,5-1,0- 0,75-0,5 and 0.25 mg/mL). To evaluate the cytotoxic activity the adult forms (metanauplius) of Artemia salina were incubated for 24 hours with the following concentrations of 1000 extracts, 750, 500, 250, 100 and 50 μg/mL, thereby groups were assigned according to their respective concentration and all tests were performed in triplicate. The result of phytochemical analysis of crude aqueous extract Tithonia diversifolia revealed the presence of saponins, organic acids, reducing sugars, phenols, tannins, alkaloids, cyanogenic glycosides, and resins. In crude ethanol extract was revealed the presence of those found in the aqueous crude extract plus protein and amino acids. It is observed a strong antioxidant activity of both the aqueous extract as ethanol dose dependent on the type DPPH • with IC50 of 2.273 and 0.630 mg / mL, respectively, for EBA and EBE. Regarding the cytotoxic activity, is observed that the aqueous crude extract of T. diversifolia was non-toxic to A. salina with CL50 equal to 3660 μg/mL. To the ethanolic extract to LC50 of 1403 μg / mL also shows no toxicity, but statistical analysis revealed that values obtained for T. diversifolia are within the probabilistic error bound suggesting cytotoxic activity by high concentrations. On the results obtained, it is concluded that the plant species is a promising source of antioxidant compounds.