Almost 40 years of clinical experience with birth control pills established their role not only as the most reliable method of contraception but also for a variety of therapeutic indications. Over the intervening decades a remarkable change in the hormone content of the various formulations has been seen: hormone quantity has decreased; multiphase formulations and different progestogens have been introduced. These changes were necessary after case reports on serious side effects during oral contraceptive (OC) use had been published.