Résumé : The amounts of luteinizing hormone (LH) and follicle stimulating hormone (FSH) released in response to the intravenous administration of 12.5, 25, and 100 μg of LH-Releasing Hormone (LH-RH) were found to be severely impeded in 4 out of 5 women who had been taking oral contraceptives for periods ranging from 12 to 36 months. Long-term administration of oral contraceptives seems to limit the reserve capacity of the pituitary to release gonadotrophins. © 1974 J. F. Bergmann.