The isoflavones have been associated with estrogenic activity and other health benefits, however, its efficiency is related with the microbiota capability of metabolizyng these compounds. This study aims to enhance the estrogenic activity and the antioxidant potential of soy milk (SM) by biotransformation of SM with Tannase Enzyme (SMT) and, as a control, with B-glycosidase Enzyme (SMB), since both enzyme have hydrolisis action. The Total Phenolic Content and DPPH assay (methanolic extract) did not present statistics differences between the samples. The SMT presented increased antioxidant potencial when compared with the control (SM) by Orac Assay and FRAP Assay. The Sulforhodamine Assay measured the MCF-7 BUS cells viability at concentrations from 0,1 to 1 µl/ml of sample; all samples increased cell proliferation when compared with the control, indicating that the SMT and SMB presented higher estrogenic activity, since this line is a human mama cancer estrogen responsive cell. All the samples presented synergy with Estradiol (E2) at E-screen assay, suggesting that SM, SMT and SMB react as phytohormone and have potential to become a alternative treatment to reduce postmenopausal symptoms.