Abstract Background: Fetal structural anomalies are present in up to 2- 3% of all pregnancies. Worldwide, second trimester scan between 18 and 22 weeks is the standard of care for fe- tal anatomical assessment; however, first trimester screening can detect almost half of all severe fetal anomalies at an early stage of pregnancy. The prenatal detection of fetal anomalies during first trimester of pregnancy allows for optimal perinatal management, providing expectant parents with opportunities for additional imaging, genetic testing, and the provision of information regarding prognosis and management options. Objective: To determine the effectiveness of the fetal ultrasound scanning at 11-13 weeks gestation in the early diagnosis of structural fetal anomalies in an unselected low risk population. Patients and Methods: This prospective follow-up study included 195 pregnant women at first trimester with low risk pregnancy at the fetal medicine unit of Obstetrics and Gyne- cology Department in Mansoura University Hospital during 2021. Ultrasound screening was performed at 11-13 Weeks in all pregnant women. For those who had normal scans a follow up scan was done at 18-22 weeks. Fetal viability was examined and crown rump length was measured. Results: In this study, we have shown the prevalence and types of congenital anomalies in the studied cases during 11- 13 weeks gestation and the associations of such anomalies with the demographic characteristics, obstetric history and CRL. Conclusion: This study shows that ultrasound diagnosis at 11–13th week gestational age is possible for some severe anomalies. We recommend the introduction of an 11–13th week scan as first part of the routine anomaly screening in pregnancy, as this enables early identification of severe anomalies.