Antiestrogens are widely used to treat eugonadal anovulation, luteal phase deficiency (LPD) and oligospermia. This paper reviews the rationales, endocrine effects, profertility effects and side effects of these treatments. Furthermore, we present our own experience of the use of antiestrogens in this field. We have compared the results of clomiphene citrate (CC) to those of tamoxifen (TAM) in a randomized study including 66 infertile women presenting eugonadal anovulation (n = 26) or LPD (n = 40). Both drugs obtained the same pregnancy rate of 80% at 9 months in the anovulatory patients. Conversely, CC was superior to TAM in the LPD cases (pregnancy rates at 6 months of respectively 40 and 11%). The abortion rates were of 11% on CC versus 36% on TAM. Both drugs significantly increased the luteal phase length and plasma progesterone level to the same extent. The results of endometrial biopsies suggest that the difference in their effects on female fertility could result from a detrimental effect of TAM on endometrium. The rates of the side effects proved to be almost identical on both drugs. Thus the use of TAM is not justified as a first-step treatment in ovulation disturbances. TAM should be reserved for patients who experience severe visual side effects on CC. We have also tested TAM in 100 subfertile males. In the 92 oligospermic males, TAM significantly increased the mean sperm count only in the normogonadotropic patients, but as much whether oligospermia was idiopathic or not. Sperm improvement was not significantly related to any hormone criterion except basal serum FSH. The cumulative pregnancy rate was of 41.2% at 1 year. Whether TAM actually improves male fertility, and is superior to CC in this indication, remains to be confirmed in controlled studies.