Abstract: Medicinal plants are organisms that are naturally endowed with chemical compounds (secondary metabolites) with properties of high therapeutic value, yielding advances in the development of synthetic drugs with physiological action beneficial to humans (ref). The use of these plants has an ancient origin in different cultures around the world and their preparation is basically in the form of extracts and teas. Medicinal plants that have a significant amount of phenolic compounds are of great interest since these compounds are attributed various activities; the most relevant is antioxidant activity, which is important in countering oxidative stress (Huie, 2002). Oxidative stress arises mainly as consecuence of the overproduction of free radicals due to inbalance in production of antioxidants by the cells (Emilien et al, 2000). Natural products especially from plant sources have the ability to reduce oxidative stress by acting as antioxidant (Irshad et al, 2012), therefore, in this work we determined the total content of phenolic compounds and antioxidant activity was evaluated of six plants used in traditional medicine for Ecuadorian indigenous ethnicities. The species collected in this study were: Potalia amara, Salvia corrugata Vahl, Ilex guayusa Loes, Scoparia dulcis, Monnina sp and Alternanthera porrigens.