MicroRNAs (miRNAs) are small, non-coding RNAs (18-25 nucleotides) that post-transcriptionally modulate gene expression by negatively regulating the stability or translational efficiency of their target mRNAs. In this context, the present study aimed to evaluate the in vitro effects of miR-153 inhibition in the breast carcinoma cell line MDA-MB-231. Forty-eight hours after MDA-MB-231 cells were transfected with the miR-153 inhibitor, an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was utilized to determine the effects of miR-153 on cell viability. Flow cytometry analysis and assessment of caspase 3/7 activity were adopted to determine whether miR-153 affects the proliferation rates and apoptosis levels of MDA-MB-231 cells. Our results showed that silencing of miR-153 significantly inhibited growth when compared to controls at 48 hours, reducing proliferation by 37.6%, and inducing apoptosis. Further studies are necessary to corroborate our findings and examine the potential use of this microRNA in future diagnostic and therapeutic interventions.