The objective of this research was to evaluate the antioxidant activity of natural and industrialized grape juices. The natural juice was produced using BRS Violeta (BRS Rúbea x IAC 1398-21) cultivar grape by steam drag method, and two commercial juices were acquired at local market. The antioxidant activity was evaluated based on DPPH radical scavenging assay, ability to capture the ABTS and ferric ion reducing power (FRAP). The phenolic compounds content also has been evaluated by Folin-Ciocalteau method. A high antioxidant activity was observed in the natural juice sample. Related to the ability to capture the ABTS, the natural sample presented 49.739 ± 2.088 mmol TEAC mL activity, while commercial samples demonstrated 70% lower antioxidant activity (14.695 ± 0.544 mmol TEAC mL-1 and 13.507 ± 0.985 mmol TEAC mL-1). Similarly, the natural juice sample showed greater ability to DPPH radical scavenging (23.669 ± 0.226 µmol TEAC mL-1) with values 66% higher than commercial sample 1 (7.995 ± 0.315 µmol TEAC mL-1) and 86% higher compared to commercial sample 2 (3.205 ± 0.308 µmol TEAC mL-1). The ferric ion reducing power (FRAP) was greater in natural sample (178.738 ± 9.230 mol Fe2+ mL-1) than commercial samples (26.357 ± 1.088 mol Fe2+ mL-1 and 23.193 ± 1.389 mol Fe2+ mL-1). The phenolic compounds content on natural juice (771.669 ±5.852 mg EAG mL-1) was much higher value than commercial juices (300.259 ± 3.577 mg EAG mL-1 and 178.826 ± 7.154 mg EAG mL-1). The results suggest that grape industrial processing for juice production substantially contributes for the reduction of total phenolic compounds content, and consequently for the final product antioxidant activity. The natural juice made from BRS Violeta can be considered a polyphenols source and a high antioxidant potential product.