The authors, basing their work on their experience over many years with a large number of cases, are proposing that synthetic progestational agents can be used at two levels of dosage, to serve as contraception and as a treatment when a progestational agent is used and is followed by micro-dosages of another progestational substance. So they prescribe at the end a of cycle following different dosages for different lengths of time, the same (or a different) progestational agent to treat breast troubles or menstrual troubles which are often intricate, particularly near the menopause. The authors in this way can compare by trials the effects of this method as compared with those of a progestational contraceptive administered in high doses and prescribed in an interrupted way and the prescription of micro-dosages of progestational agents that are taken "non-stop" which is now a classical method of treatment. This new method of contraception using progestational agents at two levels of dosage is particularly useful in patients who cannot take oestrogens because of metabolic upsets or because of tumours and who have reacted badly to the two other methods mentioned. If the dose, which can be calculated thanks to our knowledge of the hormonal background of the patient, is altered good therapeutic results and a relatively sure method of contraception is evolved without metabolic risks for the patient. This association of two progestational levels of dosage seems to be indicated particularly in women of over 40 years of age.