Background: Microwave cooking is a growing trend in the general population, which does not take into account the effect on food quality. Objective: To evaluate the effect of the extract of Bixa orellana on sunflower oil during microwave heating. Materials and methods: Sunflower oil was heated during 12 minutes in a microwave, with and without the addition of 100 mg extract of Bixa orellana, and physicochemical properties were evaluated at different time intervals. Results: The addition of Bixa orellana extract contributes to preserve the quality of the sunflower oil during the first three minutes of heating. For longer periods, no protective effect is observed. Conclusion: The addition of 100 mg of extract of Bixa orellana on sunflower oil was capable to avoid the oxidation during microwave heating for three minutes.