Progesterone is an important and unique reproductive hormone. It is the main product of the corpus luteum, dominant in the luteal phase of the cycle, and in pregnancy its secretion continues and increases ensuring maintenance of the early conceptus. At any time in these events, the suspension of progesterone action may interfere with successful reproduction. The term 'luteal contraception' was deliberately chosen for the antifertility effect achieved by the elimination of progesterone action through the use of antiprogesterones in the post-ovulatory phase of the cycle, including early pregnancy. Published clinical experience with RU 486 (Mifepristone) as a post-coital contraceptive, implantation inhibitor, once-a-month pill, menstruation regulator and early abortifacient is reviewed. The potentials and limitations of these uses are discussed and the state of art of 'contragestion' by antiprogestagen treatment summarized.