Geraniin, the natural polyphenolic compound extracted from the plant, Phyllanthus amarus sp, is used to study various diseases. It has been reported that geraniin possesses anti-tumour, anti-inflammatory, anti-microbial and anti-oxidative properties. In one of the previous investigation, it was noted that geraniin exerts the inhibitory effect on the proliferation of estrogen dependent human breast cancer cell line. In this study, the anti-tumour effects of geraniin on human breast cancer cell metabolism were investigated. This study assessed the anti-tumour effects of geraniin using various approaches such as cell viability assay, lactate assay and qPCR gene expression for the in vitro work. We have particularly investigated the effect of geraniin towards the two different breast cancer cell lines which are MCF-7 and MDA-MB-231. We would like to further investigate the treatment response between hormonal dependent (MCF-7) and non-hormonal dependent (MDA-MB-231) breast cancer cells. The results showed that geraniin exhibits the inhibitory effect against both MCF-7 and MDA-MB-231 as seen in the cytotoxicity assay. This was further strengthened by evidence of lactate assay experiment in which both MCF-7 and MDA-MB-231 revealed reduction in the lactate concentration. However, from the lactate result, MCF-7 showed significant lactate reduction as compared to MDA-MB-231. On the other hand, qPCR gene expression on the targeted genes of MCT 1, MCT 2 and MCT 4 were downregulated in MCF-7. As for the MDA-MB-231, the genes of MCT 1 and MCT 2 were also downregulated, however, it was upregulated in MCT 4. Overall, the result is promising as geraniin could have a beneficial effect in combating the breast cancer progression. In conclusion, this study shows that geraniin has powerful anti-tumour effects in estrogen dependent human breast cancer (MCF-7) than the non- estrogen dependent breast cancer (MDA-MB-231) as seen from the results. Hence, geraniin holds great potential as a chemotherapeutic agent in the treatment of breast cancer.