The defatted methanol extract of Raphanus sativus Linn. (Cruciferae) seed (MERS) was evaluated for its antisteroidogenic potential in mature female Swiss albino mice. The methanol extract at the doses of 100 and 200 mg/kg body weight significantly elevated the levels of cholesterol and ascorbic acid contents which serve as a precursor for the synthesis of steroid hormones in ovaries. The extract also significantly inhibited glucose-6-phosphate dehydrogenase and ${Delta}^5-3{eta}$-hydroxy steroid dehydrogenase, the two key enzymes involved in ovarian steroidogenesis. Hence the extract (MERS) exhibited significant antisteroidogenic activity.