Luteinizing hormone releasing hormone (LHRH) agonists have been used in conjunction with gonadotrophins, and occasionally with pulsatile LHRH, for ovulation induction in women with clomiphene-citrate-resistant polycystic ovary syndrome (PCOS) and also for superovulation for in vitro fertilization (IVF) and gamete intrafallopian transfer in women with PCOS. In IVF, LHRH agonists given by the 'long protocol' before gonadotrophins are commenced have consistently shown higher pregnancy rates and higher live birth rates. Although the optimal time to commence LHRH agonist is not clearly determined, commencement in the early follicular phase possibly with pre-treatment with the combined oral contraceptive pill would avoid the risk of inadvertent administration during early pregnancy. The role of LHRH agonists in ovulation induction is less clear cut, although there may be some advantages in patients with refractory PCOS. The role of LHRH agonists in ovarian hyperstimulation syndrome and recurrent miscarriage is also discussed.