Insulinresistance, commonly associated with polycystic ovarian syndrome (PCOS), raises many unresolved debates about its prevalence, mechanism and true pathological role. Low insulin sensibility may have multiple origins among them genetic molecular defects in pathways of cellular insulin effects. A weight gain and android distribution of fat mass may reveal or increase insulin resistance and hyperinsulinemia. The preexisting unbalanced ovarian steroidogenesis secondary to abnormalities in gene coding for enzymes of P450C17 alpha might be the necessary support facilitating the stimulatory effect of hyperinsulinemia or other factors (LH, IGF1) on ovarian androgens. In practice, the phycisian has to know how to evaluate and to treat insulin resistance in view of its implication in dysovulation and, later on, metabolic and cardiovascular risks. Nutritional education and regular physical exercice are the necessary approaches. The efficacy and indications of metformin and thiazolidinediones have to be further evaluated.