Hepcidin (TH1-5) is a cysteine-rich antimicrobial peptide originally isolated from the freshwater fish Oreochromis mossambicus. A synthesized form of the peptide has been reported to exhibit cytotoxic activity against few human cancer cell lines. This study investigated the potential cytotoxicity of the peptide against human breast cancer cell line and normal mouse embryonic fibroblast cell line (NIH/3T3) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological changes by acridine orange and propidium iodide (AO/PI) double staining were also studied to determine apoptotic evidences. Hepcidin (TH1-5) showed cytotoxic activity against MCF7 with an IC50 of 20 g/mL but no significant effect against NIH/3T3. This outcome indicates hepcidin (TH1-5) to be a promising cytotoxic peptide that warrants further studies as a potential anticancer agent for breast cancer therapy.