This is a short review on the mechanism of action of high-affinity antiestrogens at the cellular and molecular level. Past and recent data from this and other laboratories are discussed concerning the mode of action of antiestrogens in controlling gene expression and cell proliferation, including their mode of action as inhibitors of growth factor action and oncogene expression. It has been proposed that antiestrogens may not simply act to inhibit estrogen action but may also directly trigger cell growth inhibition via the estrogen receptor in the absence of estrogen. "Estrogen receptor mediated growth inhibitors" may therefore be a more appropriate and general term for defining these estrogen analogues.