Due to the different pharmacological mode of action, GnRH-antagonists seem to open up new avenues to hormonal treatment in several indications. Although it may be still too early to speculate about the possible end of the era of GnRH-agonists, from what is known today, the advantages of GnRH-antagonists are most evident in our opinion. When the development of sustained delivery systems may continue and be completed, the antagonists will have a major potential within benign gynecological conditions and also in the treatment of malignancies such as prostatic, mammary, endometrial or ovarian cancer. Suitable sustained delivery systems and the development of GnRH-antagonists with sufficient oral bioavailability, represent the present and future challenge for these efforts.