The organochlorine pesticide, dichlorodiphenyltrichloroethane (DDT), which is fat-soluble and persistent in the body and environment, has estrogenic activity. There has been an apparent association with breast cancer, which has implicated DDT binding with estrogen receptors (ERs). The mechanism of DDT-ER interaction at target sites is similar to estrogen, with protein synthesis resulting in an estrogenic response. Other than the female reproductive sites, DDT could possibly bind to ERs present in other body systems. The recent discovery of a beta receptor has introduced a new understanding of estrogen and DDT binding. An understanding of the molecular biology of the DDT-ER interaction in breast tissue could possibly explain the risk of breast cancer. Estrogen and other estrogenic compounds compete with DDT by their estrogenic potential. DDT-ER interaction in the body has wider implications in terms of its genotoxic potential and role in carcinogenesis.