INTRODUCCIÓNLas especies reactivas del oxígeno (ERO) son agentes oxidantes que tienen o son fácilmente convertidos en radicales libres, los que son átomos o grupos de átomos inestables de alta energía que poseen uno o más electrones desapareados o libres en sus orbitales exteriores, por lo que son muy reactivos ya que tienden a captar un electrón de moléculas estables con el fin de alcanzar su estabilidad electroquímica (1). Las ERO, cuyo origen es (1) ( ABSTRACT The reactive oxygen species (ERO) cause cell damage that can be expressed as a disease, including cardiovascular disease (CVD) and other non transmissible chronic diseases. The human body has antioxidant systems, some come from the diet, especially fruits and vegetables, and others are generated by the same organism as an endogenous way. The aim of this study was to determine the in vitro antioxidant capacity of some fruits and vegetables that are consumed in the Maule Region, Chile. Eleven species of fruits and 16 of vegetables used in the study were obtained at the Regional Center of Fruits and Vegetables of Talca during the harvest season, and different aqueous and methanol extract were obtained. The antioxidant activity was determined by purple discoloration of the radical 2,2-diphenyl-1-picryl hidrazilo hydrated (DPPH). In general the antioxidant activity was slightly higher in fruits (70,3%; 87,7-54,3%) than in vegetables (54,7%; 44,3-79,7%) (p ≤ 0.003) and it was dependent on the concentration of the extract. In the tests at 1000 µg/m, most fruits showed a higher percentage of discoloration over to 60%; those that showed higher antioxidant activity were raspberry, strawberry and kiwi. Among vegetables, those showing higher antioxidant activity were tomato, followed by melon pear, red beet, melon (type tuna), sweet pepper and watermelon. The antioxidant activity observed in most fruits and vegetables could be assessed as a scientific argument to make known in promotional campaigns in national consumption and the horticultural products exports.