Uncontrolled proliferation and death resistance are two hallmarks of cancer cells (1). Breast cancer has the highest incidence and mortality in women worlwide and national, subtype triple negative is the most aggressive because it is not susceptible to conventional therapy (2–4). Since 2004 OMS approved use of alternative treatments as adjuvants base don evidence of its benefits, since then have been studied differents natural alternatives to treat cancer, here stand out the Origanum vulgare (Ov) and Carvacrol (Crv), one of its main compounds, however, cytotoxic potential of these products has not been studied in this subtype of breast cancer (5–7). The objective of this study was evaluate the cytotoxic effect of the Ov and Crv on triple negative breast cancer cell line (HCC-70). Lethal dose 50 was determined on control cell line HaCaT through MTT assays with Ov and Crv stimulus in different doses and concentrations, the found dose was used on HCC-70 cell line. The results were evaluated by ANOVA, finding that Ov reduce the proliferation by 94.05% ±0.11 (p<0.001) and Crv by 93.43% ±0.21 (p<0.001) compared to untreated cells. This suggests that both the Ov and Crv presents a poweful cytotoxic effect against HCC-70 cell line and are promising optional that should continue studying.