The research conducted with the Rosmarinus officinalis L. species known as rosemary was aimed at making the phytochemical study, antioxidant activity, and toxicological analysis of ethanol crude extract of the leaves. The phytochemical analysis of the species presented as the main secondary metabolites: alkaloids, phenols and tannins, and depsides depsidones, reducing sugars and coumarins. The antioxidant activity of the species was determined by linear regression of the inhibiting concentration 50% (IC50), which showed a value of 2.24 2.24 mg/mL-1, strong correlation coefficient (R2) of 0.9425, showing its potential therapeutic, and this is an important activity for inhibiting free radicals. The toxicological analysis with Artemia salina, which is considered the life and death of metanauplius, the crude extract of R. Officinalis L. did not show in any of its concentrations death of these marine organisms, which causes the extract of the species not present toxicity at the concentrations tested.