Diethylstilbestrol (DES) is a nonsteroidal synthetic estrogen presently used in the treatment of ovarian insufficiency, in the palliative treatment of breast malignancy, and as a contraceptive when used postcoitally. It was formerly used to prevent miscarriages, but was found not to be efficacious for this purpose. In the human, as pointed out on the package label, DES proved to have significant transplacental developmental effects leading to carcinogenesis in the genital organs of females and adverse developmental effects in male offspring. Herbst and associates, after reporting the association between intake of DES by women during pregnancy and the induction of vaginal cancer in their daughters, established a registry of clear cell adenocarcinoma of the genital tract in young females in 1971. Diethylstilbestrol is an average-sized human developmental toxicant. It is of low polarity and high hydrophobicity. It can participate in hydrogen bonding to a certain extent both as an acceptor and donor.