Cancer represents a worldwide public health problem, with high incidence and mortality rates in developed and undeveloped countries. Cur-rently, therapeutic alternatives of natural origin are being evaluated with the purpose of establishing more efficient and less invasive treatments. Apoptosis is the type of programmed death cancer cells undergo during treatment with anti-neoplastic drugs. Therefore, the aim of this research was to evaluate in vitro the pro-apoptotic and cytotoxic capacity of valerian extracts on a breast cancer cell line (MCF-7). In this study, MCF7 cells were cultured and treated with different concentrations of the extracts of the root, leaves and stems of Valeriana rígida and Valeriana decussata. Cell viability was assessed by the MTT assay. Quantitative reverse transcription PCR assays were used for the determi-nation of gene expression of anti- and proapoptotic proteins (Bax, Bcl-2, p53). Different concentrations of the extracts (10–8 to 10–1 mg/mL) decreased cell viability (proliferation) in a concentration-dependent manner. These extracts induced gene expression of Bax and Bcl-2 proteins but not of p53. The expres-sion of Bax was higher than that of Bcl-2, causing an elevated Bax/Bcl-2 ratio (proapoptotic condition). In conclusion, it was determined that Valeriana de-cussata and Valeriana rígida extracts have a viability (proliferation) reducing effect on the MCF-7 breast cancer cell line, probably mediated by altering the ratio of Bax and Bcl-2 proteins linked to apoptosis.