The objective of this study was to investigate the antioxidant and antimicrobial effects of the addition of yerba mate extract on chicken breast meat to increase the shelf life. Fresh chicken breast meat was divided into five treatment: negative control with no extract (NC), 0.05% (0,05EM), 0.10% (0,1EM), 0,15% (0,15EM) and 0.20% (0,2EM) of yerba mate extract. In order to evaluate the antioxidant effect, TBARS method (Thiobarbituric Acid Reactive Substances) was applied in pre-cooked meatballs to measure the accumulation of secondary lipid oxidation compounds during cooking on days 0, 2, 4, 6, 8 and 10 of chilled storage (4 °C). The antimicrobial activity was evaluated in raw chicken meat stored at 7 °C by counting the amount of total mesophilic bacteria, psychrotrophic bacteria,molds and yeasts every two days (days 1, 3, 5 and 7). E. coli and P. mirabilis isolated from the chicken meat was used to perform a disc diffusion test using different extract concentrations (125mg/ml, 250mg/ml, 550mg/ml, negative control (solution saline 0.85%) and pure yerba mate). The addition of 0.10%; 0.15% and 0.20% yerba mate extract effectively protected lipids during cooking, since no differences (P>0.05) were found in TBARS values between raw and cooked samples. The addition of yerba mate extract to chicken meatballs reduced (P <0.0001) the production of secondary lipid oxidation compounds acting as a natural antioxidant in pre-cooked meatballs during 10 days of chilled storage regardless the concentration used, when compared to NC. It was observed a quadratic regression (P <0.0001) in which TBARS values reduced as the addition of yerba mate increased and it was possible to estimate that 0,18% of yerba mate was the most effective concentration to control lipid oxidation in this study. The total mesophilic and psychrotrophic bacteria count was statistically reduced (P <0.05) as the addition of yerba mate increased only on day 1. For molds and yeasts, increasing yerba mate addition reduced linearly (P<0,05) the count on day 1 and quadratically (P<0,05) on day 3. Increasing addition of yerba mate extract also increased (P<0,0001) inhibition for E. coli and P. mirabilis and the treatment with pure yerba mate showed the most effective treatment against both bacteria. The yerba mate extract showed in vitro antimicrobial activity against the studied bacteria, however, did not exhibited microbial growth control when added to raw chicken breast meat during 7 days of chilled storage, not contributing to the extent of shelf life.