The chemical composition, antioxidant or anti-proliferative activities of essential oils from leaves of Schinus areira L. and Minthostachys spicata (Benth.) Epl. grown in Cuzco (Peru) was studied. Fifty-six and fifty-eight compounds were identified in the essential oils from S. areira and M. spicata leaves, respectively. In S. areira essential oil, monoterpene hydrocarbons were the most represented class of volatiles (58.7%), including α-phellandrene, limonene, camphene, β-phellandrene, α-pinene, p-cymene, and β-pinene as the major components. In M. spicata, oxygenated monoterpenes (87.4%) were the major class of volatiles; among them pulegone, isomenthone, and menthone were the main compounds. Antioxidant activity were examined using 1,1-diphenyl-2-picryl-hydrazyl assay. Essential oil from S. areira was also evaluated for its anti-proliferative activities against murine breast cancer cells (4T1). Our results justify the use of these plants in traditional medicine in Peru and open a new field of investigation in the characterization of the molecules involved in the antioxidants and anti-proliferative processes.