There is no doubt that there is a wide range of clinical application for GnRH analogues within the field of Gynaecology. Both the indication and varying degree of suppression of the hypothalamic-pituitary-ovarian-axis are depicted in Table 3(34). This review focuses only on the use of GnRH agonist in the treatment of endometriosis, uterine leiomyoma, infertility in polycystic ovary syndrome and in IVF/GIFT programmes. In Thailand, this drug has achieved an important role in clinical therapy in just over the past few years and until now buserelin is the only preparation which is available.