Background: evaluation of ovarian reserve has become an essential part of the treatment assessment of woman to undergo assisted reproductive technique. Aim of the Work: this work was conducted to measure FSH, LH and E2 at any day of the whole menstrual cycle compared to day2 with measurement and establishing an actual negative correlation between FSH & E2. Patients and methods: observational analytical prospective study on 50 women attending the Gynecology Outpatient Clinics of Maternity Hospital, Ain-Shams University in 2016. Results: there was a significant negative correlation between E2/FSH on the 3^rd, 5^th and 10^th days of the cycle. Also there was insignificant negative correlation on day 21. Conclusion: there was negative correlation between basal day2 E2/FSH which was equivalent or similar to that ratio on days (5,10,21) so there was no need to wait for hormonal analysis to the next cycle (day 2 or 3) to save time specially in patients >35years; for them there was importance of cycle day3 for evaluation of ovarian reserve and prior ovulation induction and subsequent pregnancy potential during the infertility work up. Recommendations: during the infertility work up, rigid adherence to cycle day3 collection, no longer seems necessary ,no need to wait for hormonal analysis to Estradiol and FSH to the next cycle as there was equivalent negative correlation between E2/FSH on menstrual cycle days (3,5,10,21) aiming for saving time.