Résumé : A novel series of estrone derivatives having a free 3‐phenolic group with the 2‐ or 4‐position substituted with a thiourea function was synthesized. None of the products showed significant binding to the estrogen receptor, and the cytotoxic activity on MCF‐7 cells for VII and X was weak. Copyright © 1984 Wiley‐Liss, Inc., A Wiley Company