Objective: To determine if there is any added value of 3D US examination in diagnosis of fetal malformations during mid-trimester anomaly scan.  Design: A prospective observational study.  Setting: Obstetrics and Gynecology Ultrasound Unit, Zagazig University Hospitals.  Patients and Methods: Pregnant women referred for mid-trimester anomaly scan were prospectively evaluated by 2D US. Fetuses suspected to have malformation by 2D US or with increased risk of a recurrence or strong family history of a congenital abnormality were evaluated by 3D US. Women confirmed to have fetal malformations postnatally were included.  Results:Seven hundred and seventy-six malformations were confirmed postnatally. 2D US established the diagnosis of 752 (96.9%) malformations and 3D US diagnosed 770 (99.2%) malformations and the difference was highly significant [McNemar chi-squared statistic= 16, p=˂0.0001]. Seven hundred and fifty-two malformations were diagnosed by both 2D and 3D US. Eighteen malformations were detected exclusively by 3D US. 3D US was superior to 2D in evaluating cranial, facial and limb malformations. A cleft soft palate, hand abnormalities (n=3) and feet abnormalities (n=2) were missed by both 2D and 3D US.  Conclusion: Three dimensional US added value in diagnosis of some types of fetal malformations. Rather than representing an alternative, 3D US is complementary to the conventional 2D US in the field of prenatal diagnosis.