RESUMEN
The use of exogenous gonadotropins, alone or in association with other drugs, is a useful tool in the treatment of anovulation. The first stages of the follicologenesis are gonadotropin independent up to the preantral stage. The final phase of this process begins when follicles grow faster during the luteal phase of the preceding cycle, the so-called gonadotropin-dependent phase. Recent studies confirmed the central role of FSH in follicular and oocyte maturation, but also re-evaluated the actions of LH, in particular during the first phases of these processes. LH induces the physiological development of the follicle, acting only on a limited number of follicles, while FSH protects against atresia. In the absence of FSH the development will be delayed. It seems obvious that both hormones are necessary, that a stimulation protocol may rely only on FSH, but the addition of LH will render it more physiological.