Isoflavones, from soy and other plant sources are of interest because of their estrogenic, antifungal, and antibacterial activities. Soybeans contain three major isoflavones: genistein, daidzein, and glycitein. Soy isoflavones share structural features with the animal estrogen, 17-ß estradiol. This structural similarity allows these compounds to bind to estrogen receptors and sex hormone binding proteins. Considering the estrogenic activity of soy isoflavones, it is important to understand how these compounds affect the reproductive hormones and also knowingthehealthaspects of these compounds.