MicroRNAs (miRNAs) are small, non-coding RNAs (18-25 nucleotides) that post-transcriptionally modulategene expression by negatively regulating the stability or translational efficiency of their target mRNAs. In thiscontext, the present study aimed to evaluate the in vitro effects of miR-485 mimics in breast carcinoma T47D cells.Forty-eight hours after T47D cells were transfected with miR-485 mimics, an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was utilized to determine the effects on cell viability. Colony formationand cell migration assays were adopted to determine whether miR-485 affects the proliferation rates and cellmigration of breast carcinoma T47D cells. Our results showed that ectopic expression of miR-485 resulted in asignificant decrease in cell growth, cell colony formation, and cell migration. These findings suggest that miR-485 might play an important role in breast cancer by suppressing cell proliferation and migration.