Introduction: Bixa orellana L. also known as annatto, is a plant with a high content of bioactive compounds, such as saponins, alkaloids and flavonoids that have physiological properties as antimicrobial, anti-inflammatory, anti-allergenic, antiviral, anticarcinogenic and antioxidant properties, among others. Objectives: To evaluate the effect of extraction time and the solvent/ leaf ratio over the total phenolic content and the effect of solids and pH of the solution on the antioxidant activity in extracts from Bixa orellana leaves. Methods: The ethanol extract of leaves of Bixa orellana was obtained by percolation and filtering. Total phenol content was evaluated by the Folin-Ciocalteu. The antioxidant activity was determined by spectrophotometric methods as reaction with 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) and ferric reducing antioxidant power, the results were expressed as micromoles of Trolox equivalents per gram of extract (μmolTE.g -1). Results: Process conditions that improve the extraction of phenolic compounds from Bixa. orellana extract are: extraction time of 60 h and solvent/ leaves ratio (v/w) of 4/1. The maximum total phenol content was 144.77 ± 9.66mgAT.g-1, which when subject to a solution of pH 8 and 11.7 °Brix, has an antioxidant activity of 4406.83 ± 43.30 μmolTE.g-1 by the 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) reaction and 4547.22 ± 53.19 μmolET.g-1 by ferric reducing antioxidant power. Conclusion: It showed that the amount of TF extracted from leaves of Bixa orellana depend on the solvent/ leaves ratio and the extraction time. In addition, it found that the pH has an effect on the antioxidant activity determined by the methods 2,2'Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) reaction and ferric reducing antioxidant power.