Background: Over the last two decades, various ultrasound markers have been investigated to evaluate their role in the prediction of ovarian function and hence reserve. The three most common markers that have been specifically addressed are ovarian volume, antral follicle count (AFC) and ovarian vascularity. Objective : To evaluate differences between  three-dimensional (3D) and two dimensional(2D) ultrasound markers of ovarian reserve (antral follicle count and ovarian volume ) in women undergoing investigation for subfertility before intra cytoplasmic sperm injection.                       Patients and methods: This study was a prospective observational study including 50 women who attend the Infertility Clinic at Al-Azhar International Islamic Center for population studies and researches. Intervention: Measurement of cycle day three follicle stimulating hormone (CD3 FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E2), anti Mullerian hormone (AMH), thyroid stimulating hormone (TSH) and ovarian reserve{antral follicle count (AFC) and ovarian volume (OV) }by transvaginal tow dimensional (2D) and three dimensional (3D) ultrasound , patients were subjected to long ovulation induction protocol. Assessment of  follicles number, quality and number of oocyte retrieved was done. Results: There was no difference between 2D and 3D ultrasound in the assessment of antral follicle count. The difference between 2D and 3D ultrasound in the assessment of ovarian volume was minimal and non-significant. Conclusions: Application of transvaginal sonography in evaluation of ovarian reserve  proved to be of important value  in the assessment of poor and good responders for ICSI treatment, to avoid expensive IVF cycle cancellation.