Background: unsuspected uterine cavity abnormalities, such as endometrial polyps, small submucous myomas, adhesions, and uterine septum may cause different gynecological complaints such as bleeding and negatively impact chances of success in ART by interfering with implantation or causing spontaneous abortion. Therefore, exclusion of intrauterine pathology is an important step before starting ART and treatment of any discovered lesion may improve ART outcome. The uterine cavity can be evaluated by hysterosalpingography (HSG), transvaginal ultrasound (TVS), sonohysterography (SHG), and hysteroscopy. Hysteroscopy is the gold standard for investi-gation of the uterine cavity, particularly when pathology is suspected. Objective: to assess diagnostic accuracy of three dimensional transvaginal ultrasound (3D-TVS) compared with hysteroscopy in detecting uterine cavity abnormalities.  Study design: this prospective observational cross-sectional study was conducted during the January 2018 to June 2018. One hundred women with different uterine pathologies were enrolled. In the mid to late follicular phase of each subject's menstrual cycle, three D transvaginal ultrasound and hysteroscopy were performed in each patient. Hysteroscopy is widely considered to be the gold standard method for investigation of the uterine cavity. Uterine cavity characteristics and abnormalities were recorded. Diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and positive and negative likelihood ratios were evaluated.  Results: hysteroscopy was successfully performed in all subjects. Hysteroscopy diagnosed pathological findings in 100 of 100 cases (100%). There were 50 endometrial polyps, 13 submucous myomas, 29 septate uterus, and 8 intrauterine adhesions. Three-dimensional transvaginal ultrasound in comparison with hysteroscopy had 85% diagnostic accuracy, 68.2% sensitivity, 91.5% specificity, 79% positive predictive value, and 86% negative predictive value. The positive and negative likelihood ratios were 8.01 and 0.3, respectively. 3D-TVS successfully detected every case of submucous myoma. For detection of endometrial polyps, 3D-TVS had 80.0% sensitivity, 100.0% specificity, and 90% diagnostic accuracy. For detection of septate uterus, 3D-TVS had 93.10% sensitivity, 100.0% specificity, and 98% diagnostic accuracy. Conclusion: three D-TVS demonstrated 84.1% diagnostic accuracy for detecting uterine cavity abnormalities in infertile women. A significant percentage of patients had evidence of uterine cavity pathology. Hysteroscopy is, therefore, recommended for accurate detection and diagnosis of uterine cavity lesion.