More than 60% of patients with polycystic ovary disease (PCO) cannot conceive after repeated ovulation inductions with Clomifene citrate although there is ovulation or more frequently follicle luteinization. Because of hyperstimulation, therapy with hMG has been superseded by low doses of purified FSH with variable results according to authors. It has been even claimed that there was no benefit to replace hMG with FSH. However, on the basis of the PCO physico-pathology, namely LH hypersecretion and androgen hyperproduction, it would be rational to associate the desensitization of the pituitary with LH-RH agonist and the ovary stimulation with variable doses of hMG or purified FSH. In the series where such therapy associating LH-RH agonists with purified FSH was applied, the results concerning suppression of LH and androgen secretion, and the occurrence of pregnancy were interesting. However, the risk of hyperstimulation still occurred. Thus, the first part concerns the critical review of these results while, in the second part, our experience in in vitro fecundation will be reported.