Empirical use low-dose clomiphene citrate has been advocated by some practitioners to enhance fecundity in women with unexplained infertility. No clinical trials have examined the efficacy of such treatment in the patient population, although certain studies have shown that active ovulation induction can be effective in women with unexplained infertility, and that cycle fecundity is improved for normally cycling women with active ovulation management in a program of artificial insemination. Since clomiphene citrate can have paradoxical effects on fertility through its anti-estrogenic mode of action, the benefit or lack of benefit from treatment with clomiphene citrate in this patient group needs to be evaluated. We aim to establish a dose response of FSH and LH to various low doses of clomiphene citrate in normally cycling women of known fertility, that is women with an intact hypothalamic-pituitary-ovarian-axis. The significance of this information is that it may help to elucidate the mechanism by which low-dose clomiphene citrate may improve fecundity in patients with unexplained infertility as it is currently being used empirically.