Ovarian hyperstimulation (OHS) and multiple pregnancy are dreaded complications of ovulation induction. The use of pulsatile GnRH permits to prevent the occurrence of OHS and results in few multiple pregnancies. Low-dose GnRH administration, avoidance of preovulatory hCG, patient selection, and the use of GnRH agonist pituitary desensitization in selected patients permits to limit multiple conceptions to a level comparable with the occurrence of this complication in normal unstimulated women.