Polycystic ovary syndrome accounts for more than 75% of cases of anovulatory infertility. The mechanism of anovulation is uncertain but there is evidence that arrested antral follicle development is associated with the abnormal endocrine profile, in particular the interaction of insulin and LH on granulosa cell differentiation. In terms of management, induction of ovulation can be achieved in most cases by the use of antiestrogens. Treatment of clomiphene-resistant subjects is difficult; conventional doses of gonadotropins are associated with high rates of ovarian hyperstimulation syndrome and multiple pregnancy. On the other hand, low-dose gonadotropin therapy has proven effective in inducing unifollicular ovulation and, in this review, we present, in detail, a recent analysis the results from this center. The cumulative conception rate after six cycles was more than 50% and, importantly, the multiple pregnancy rate was only 3%. W eight reduction in obese subjects with PCOS not only increases the chance of fertility but may also improve the long-term p rognosis with regard to development of diabetes. Insulin-sensitizing drugs such as metformin may also have a place in treatment of PCOS.