Over the past three decades, a substantial body of evidence has accumulated on the estrogenic activities of numerous environmental compounds. These "environmental estrogens," consisting of pesticides and a variety of industrial chemicals and their by-products, are becoming ubiquitous in the environment and are making their way into the food chain. An important issue is whether vertebrate animals are equipped with mechanisms for the inactivation and/or disposal of environmental estrogens. This review attempts to summarize the currently available data concerning the sulfation of environmental estrogenic compounds by the cytosolic sulfotransferases in vertebrate animals. (c) Pesticide Science Society of Japan.