ABSTRACT Objective: This study aimed to evaluate the role of three dimensional (3D) ultrasound compared with two dimensional (2D) ultrasound in diagnosis of fetal central nervous system congenital malformations. Patients and Methods: this Prospective study was performed on total 100 patients with gestational age from 18 weeks to 24 weeks who underwent 2D ultrasound then examined by 3D ultrasound at Obstetrics and Gynecology Department, Bab el-Sheria, Al-azhar University Hospital. Results: Statistical analysis revealed that the most common neurological malformations detected were Holoprosencephaly and Anencephaly which had significant high agreement between 2D and 3D regarding their diagnosis. There was significant agreement between 2D and 3D regarding the congenital fetal spinal and cranial malformations. The 2D and 3D ultrasound provided equal diagnostic information in microcephaly while 3D US provided more diagnostic information than 2D US for Choroid plexus cyst, agenesis of the corpus callosum and spina bifida. Our study revealed that the 3D US was superior to 2D US in identifying small cranial malformations as choroid plexus cyst and the spine e.g Spina bifida. Conclusion: In comparison with 2D US, 3D US improves the diagnostic capability by illustrating more diagnostic details in evaluation of malformations of the fetus, especially in visualization of fetal malformations of the small cranial anomalies and spina bifida . In addition to 2D US, 3D US is a valuable adjunct in prenatal detection of anomalies.