This review outlines the historical background of environmental endocrine disruptor issues and the particular sensitivity of the developing animals to exposure to estrogenic agents in the induction of longterm changes in reproductive and nonreproductive organs, and research needs of adverse effects of endocrine disruptors in experimental animals, wildlife and humans. Many chemicals released into the environment disrupt the endocrine system in wildlife and humans, and many of which have estrogenic activity by binding to the estrogen receptor. The animal and cell culture models can be utilized as an indicator of possible consequences of exposure to environmental endocrine disruptors. In humans, although the causes are not clear, hypospadia increased twice from 1970' and sperm count decreased and testicular cancer incidence increased. Epidemiological studies are needed to clarify the cause of these abnormalities in humans. More attention should be paid to abnormalities in genital organs exposed to endocrine disruptors during fetal and early postnatal development in wildlife, experimental animals and humans.