RESUMEN
AIM: To examine the efficacy of aromatase inhibitor in the induction of ovulation. METHODS: This prospective clinical trial in patients with infertility and poor response to clomiphene citrate (CC) was undertaken in a tertiary referral infertility clinic. Thirty-five infertile patients, who were treated by clomiphene citrate for several cycles and referred to the infertility clinic, were the target population. Initially, the response of CC was assessed by same dose of CC that the patient had in her last cycle. The patients who did not respond adequately were treated by aromatase inhibitor 2.5-5 mg/day from day 3-7 of the menstrual cycle. The main outcome measures were the number of mature follicles, ovulation rate, endometrial thickness and pregnancy rate. RESULTS: Twenty-seven (90%) patients developed mature follicles by day 12. The majority (77.77%) developed single follicle. Except for one cycle of one patient, the follicles of all patients were ruptured in all cycles and seven (25.94%) got pregnant. CONCLUSION: The aromatase inhibitor letrozole is effective for ovulation induction in anovulatory infertility in patients that failed to ovulate by CC.