Abstract The aim of this work was to determine (1) the total phenolic compound ( TPC ), total flavonoid compound ( TFC ) and bixin and norbixin content of polar extracts of leaves ( ALE ) and seed ( ASE ) from annatto ( B ixa orellana L .); (2) the antioxidant activity, the ALE and ASE by means of different antioxidant tests, and (3) the effectiveness of ALE and ASE on the growth inhibition of several bacterial strains. Five different test systems were used to determine the antioxidant activity, while the microdilution method was used to test for antimicrobial activity. ALE presented higher ( P < 0.05) TPC and TFC than ASE . As regards antioxidant activity, at all the concentrations tested and with all the methods, except the R ancimat test, the ALE samples showed higher ( P < 0.05) antioxidant activity than ASE samples. As regards antibacterial activity, ASE was a stronger inhibitor ( P < 0.05) of bacterial growth than ALE . Both ALE and ASE could be used as alternative natural preservatives in food matrices due to mainly their broad antioxidant activity and lesser extent of their antibacterial activity. Practical Applications The B . orellana seed and leaf extracts could be suitable for application in on the food industry because It is an important source phenolic, flavonoids and carotenoids compounds, the antioxidant properties of which could be very appreciated in a big number of food processing to avoid its oxidation not only during processing but also during storage period. However, their antimicrobial action is limited. Other important reason for their suitability is their natural origin, which consumers find comforting.