The effectiveness of tamoxifen and clomiphene in inducing ovulation was compared in 46 women with anovulatory infertility. All the women were given both the drugs in an alternate way. If one cycle was treated by tamoxifen the next was treated by clomiphene and vice versa. Forty-one out of the 46 women (89.1%) ovulated at least once during the study. Similar ovulation rates were achieved by tamoxifen (56.2%) and clomiphene (62.9%). The lengths of the ovulatory cycles and their luteal phases and the mid-luteal phase serum progesterone levels did not differ significantly between the two compounds. Nor did the occurrence of luteal phase defects during the tamoxifen and clomiphene treatment cycles differ. Thirty-seven of the 46 women (80.4%) responded similarly to both drugs. Thus, tamoxifen is just as effective as clomiphene in inducing ovulation in women with anovulation.