Background: Breast cancer is the most common type of malignancy in women. Despite dramatic achievements in the development of synthetic pharmaceutics, herbal drugs still remain as one of the leading therapeutic strategies for cancer. In the current study, we aimed to investigate the toxic effects of dendrosomal nanocurcumin on 4T1 cells derived from BALB/c mice breast tumors. Materials and Methods: For this purpose, MTT assay was exploited to evaluate viability of 4T1 cell line and mouse skin normal fibroblasts (MEF) cells under exposure to nanocurcumin. Cultured cells were treated with different concentrations of nanocurcumin ranging from 5 to 45µM. Furthermore, the effect of nanocurcumin on cells was compared with doxorubicin as a frequently-used chemotherapeutic for breast cancer. Results: The results of MTT assay indicated that treatment with nanocurcumin leads to a significant reduction in the viability of cancer cells in a dose- and time- dependent manner with no significant effect on normal cells. The decrease in viability of cancer cells was 35, 25 and 15µM for 24h, 48h and 72 h post-treatment, respectively. The data also shown that nanocurcumin exerts toxic effects the same as doxorubicin on cancer cells. Given less toxicity of nanocurcumin on normal cells in comparison with doxorubicin, this finding is of paramount importance. Conclusion: Dendrosomal nanocurcumin is able to eradicate cancer cells in a dose- and time-dependent mode. This nanodrug has toxic effects on breast cancer cells with no toxicity on breast normal cells. On the other hand, this therapeutic agent is as potent as doxorubicin in killing cancer cells. While compared with doxorubicin, this compound shows less toxicity on normal cells.