The results from this investigation showed that L. plantarum and L. acidophilus are capable of growing in pomegranate juice and metabolizing sugars, organic acids and phenolic compounds. The production of lactic acid, followed by formic and acetic as the main organic acids produced, was more intense by L. plantarum. Fructose and glucose were utilized significantly as energy source by both bacteria. The free radical scavenging effect of the juice was increased through fermentation; however, the enhanced effect of fermentation varied with the employed bacteria since L. acidophilus exhibited higher improvement in the antioxidant activity of the juice. Improvements in the radical scavenging effect can be related to the increase in the free form of phenolic compounds and the production of other by-products through fermentation. These findings highlight the beneficial effect of pomegranate juice fermentation by the incorporation of probiotic bacteria able to produce organic acids and improve the antioxidant activity of the juice