Aromatase inhibitors (AI) block the last enzymatic step of estrogen production, the aromatization of the A-cycle of aromatizable androgens and particularly, androstenedione (D4) and testosterone (T). Molecules designed for interfering with aromatase activity have existed for many years. Yet the activity of products of the aminogluthetimide era was too unspecific and these substances carried too many side effects for being used clinically. Today, however, 3rd generation AIs have become available that are highly specific and essentially devoid of side effects. These molecules have recently been approved for treating breast cancer in post-menopausal women, either in advanced forms, or as part of adjuvant therapy. In women whose ovaries are active, a temporary inhibition of E2 production will activate gonadotropins and in turn, stimulate follicular growth. In cancer patients, this property precludes the use of AIs in women whose ovaries are still active, unless gonadotropins are blocked. In infertile patients, this property of AIs has been put to play for inducing ovulation. AIs have been used both in women who do not ovulate but whose hypothalamo-pituitary-gonadal (HPG) axis is active (oligo-anovulators of PCOD type) and in those who ovulate regularly but in whom multiple ovulation is sought for treating infertility or as part of IVF. Like CC, AIs are not usable in women whose gonadotropins are suppressed, as in the case of hypothalamic amenorrhea. The sum of data available on the use of AI for inducing ovulation remains however meager to this date and is mainly constituted of pilot and non-randomized trials. Yet mounting evidence tends to support AIs' advantages over CC for induction of ovulation. Hence, we think that these drugs will play a key role for the induction of ovulation in the future.