Phytoestrogens are non-steroidal, polyphenolic compounds that are derived from plants and have biological properties similar to those of human estrogens. Their bioactivity, which is based on the core ring system, is caused by their structural resemblance to estrogen. Flavonoids, coumestans, lignans, and stilbenes are the four major categories into which they can be divided. They are structurally and functionally related to ovarian and placental estrogens, which are essential in female reproductive processes. Phytoestrogens are present in numerous dietary supplements and find application in hormone replacement therapy as an alternative to synthetic hormones. In addition, they provide health benefits for osteoporosis, heart disease, breast cancer, and prostate cancer. There is a growing interest in using phytoestrogen as preventative medicine in the form of nutraceuticals. This literature provides comprehensive information about the types, sources, and biological actions of phytoestrogens in the reproductive system.