Department of Obstetrics and Gynecology, Samsung Medical Center,Sungkyunkwan University School of Medicine, Seoul, Korea Neural tube defects (NTDs) are one of the most common fetal anomalies with the prevalence of 1-5 among 1,000 births. There are three different types of isolated NTDs: anencephaly, spina bifida, and encephalocele. Maternal serum alphafetoprotein (AFP) testing and ultrasound imaging are two mainstays in screening and detecting these fetal anomalies. Recently, as the fetal anatomic survey in the second trimester has become an integral part of prenatal care in most developed countries, sonography has largely superseded maternal AFP as a screening tool. With this background, this review offers the summary of ultrasonographic features in detecting fetal NTDs and mentions the usefulness of 3D ultrasound and fetal magnetic resonance imaging (MRI) in detecting these anomalies briefly.