Steroid hormones such as oestrogen and progesterone play multidimensional role in regulation of reproduction, metabolic and neuroendocrine functions in humans and animals. Phytoestrogens bind to oestrogen receptors and mimic the role of oestrogen, thus play a role in the management of fertility as well as therapy of hormone dependent cancers. The whole plant of Boerrhavia diffusa was collected locally from the campus of College of Veterinary and Animal sciences, Mannuthy, Thrissur. The qualitative phytochemical analysis was performed on the methanolic extracts of Boerrhavia diffusa for the presence of steroids, alkaloids, tannins, phenolic compounds, flavonoids, diterpenes, triterpenes and saponins [1]. In the present study, methanolic extract of whole plant of B. diffusa was analysed for its modulatory activity on steroidogenesis. The cytotoxicity of methanolic extract of B. diffusa was explored using MTT assay in MCF-7 cells and IC50 was calculated. The cells were also cultured in six well plates and exposed to (IC50, 2 times IC50 and half dose of IC50) for 96 hours. The culture media were collected every 48 and 96 hours, was stored at -80 °C and used for the estimation of progesterone and oestrogen by ELISA. The phytochemical analysis revealed the presence of alkaloids, glycosides, tannins and flavonoids. Through the MTT assay the IC50 of methanolic extract of B. diffusa was found to be 170 µg/mL. The methanolic extract of B. diffusa showed significant increase in the progesterone concentration with maximum increase at 340 and 170 µg/mL. There was a significant decrease in oestrogen concentration when exposed to extracts at 96 hours post treatment with maximum decrease at 340 µg/mL. Hence it could be concluded that the methanolic extract of B. diffusa down regulated oestrogen synthesis independent of the interconversion of cholesterol to progesterone. Hence the effect may be in the pathway of conversion of progesterone to oestrogen.