ICSI (Intra cytoplasmic Sperm Injection) has been the treatment of choice in severe tubal infertility &for most other indications (male factors, ovarian dysfunction, tubal disease, endometriosis and uterine or cervical factors); ICSI is applied as the last resort therapy of infertility after the failure of other treatment modalities. Implantation is the final and most crucial step in ICSI , but also the least successful, as a few embryos replaced in the uterine cavity will result in a clinical pregnancy. The majority of women undergoing ICSI will reach embryo transfer (ET) stage, with good quality embryos available for transfer, but only a small proportion of them will ever achieve a clinical pregnancy or live birth. The most important factor for successful embryo transfer is not touching the endometrium of the fundus with replacement of the embryo in the lumen of the uterine cavity. Our study aimed to study the effect of the depth of embryo transfer into the uterine cavity on the success of ICSI cycle. Methods:  This prospective cohort study was conducted at a private center starting from January 2020 to January 2022 . This study was conducted upon 120 women undergoing frozen ICSI cycle and they were divided into two groups: Group I :  included 60 cases in whom the depth of embryo transfer was (>10 <15 mm) from the uterine fundus. Group II :  included 60 cases in whom the depth of embryo transfer was  (≤10 mm) from the uterine fundus. Results: In this study, Age in group I ranged 25-33 with mean value 28.1±3.65 and in group II ranged 26-35 with mean value 29.1±3.15. There was no statistical significant difference between the two studied groups regarding age ( p value >0.05). BMI in group I was ranged 25-33.7 with mean value 28.3±2.0 and in group II ranged 24.69-31.6 with mean value 28.20±1.74. There was no statistical significant difference between the two studied groups regarding BMI ( p value >0.05). Duration of infertility in group I was ranged 2-5 with mean value 3.10±0.98 and in group II was ranged 2-4.5 with mean value 3.45±0.87. There was no statistical significant difference between the two studied groups regarding duration of infertility ( p value >0.05). Tubal factor in group I was 24 cases (40%) and in group II was 29 cases (48%), idiopathic factor was 19 cases(32%) in group I and 12 cases (20%) in group II, male factor in group I was 17cases (28%) and  19 cases (32%) in group II. Primary infertility  was 48 cases (80%) in group I and 50 cases (84%) in group II, secondary infertility  was 12 cases (20%) in group I and 10 cases (16%) in group II. In group I, number of embryo transferred ranged 2.1with mean value 1.25±0.33 and in group II ranged 2 with mean value 1.21±0.37. There was no statistical significant difference between the two studied groups regarding the number of embryo transferred. ( p value >0.05). In group I, Endometrial thickness on day of ET mean ± sd was  (11.2 ± 2.08) and in group II was (12.1 ± 2.2). There was  statistical significant difference between the two studied groups regarding the Endometrial thickness on day of ET in group I ( p value <0.05). As regarding items of fullness of bladder , ease of transfer , use of tenaclum and vaginal bleeding at time of embryo transfer there were no statistical significant difference between the two studied groups ( p value >0.05). Moreover, Positive outcome was 25(41.7%) for 0.5-1.0cm and 37(61.5%) for >1cm.-5.1cm, while negative outcome was 35(58.3%) for 0.5-1.0 and 23(38.5%) for >1cm -1.5cm. There was statistical significant difference between group I (>10 <15 mm) from the uterine fundus  with group II) ≤10 mm   (P< 0.05). Conclusion: Measuring the depth of embryo transfer into the uterine cavity has a significant role in improving success of ICSI cycle. The embryo transferring depth between (10mm and 15mm) significanty improve ICSI cycle success rate.