Background: One definition of infertility that is frequently used by reproductive endocrinologists, the doctors specialized in infertility, to consider a couple eligible for treatment if: A woman under 35 has not conceived after 12 months of contraceptive-free intercourse. Twelve months is the lower reference limit for Time To Pregnancy (TTP) by the World Health Organization. A woman over 35 has not conceived after 6 months of contraceptive-free sexual intercourse. Clomiphene citrate (CC) is the most common and simple method in ovulation induction in women with normogonadotropic anovulatory infertility. Clomiphene is a non-steroidal triphenylethele derivative with both estrogen agonist and antagonist properties .although climiphene citrates acts as antiestrogenic factor in almost of cases .it has a weak estrogenic action which appear when endogenous levels are very low . Clomiphene is cleared through the liver and excreted in the stool, approximately 85% is eliminated with a weak, but traces can remain in the circulation for longer. Sildenafil citrate is a non-steroidal compound that works as anti-oestrogen. It blocks oestrogen receptors at the hypothalamus, releasing it from negative feedback, and augmenting its release of GnRH. Subsequently, pituitary production of gonadotropins is increased resulting in follicular growth, and ovulation.