ABSTRACTCystic hygroma (CH) is the most frequently seen fetal neck mass on the first-trimester ultrasound (US). Overall prognosis is poor with a high association with chromosomal and structural anomalies. When diagnosed prenatally, fetal karyotyping and detailed US evaluation should be offered. Prenatal and postnatal surgical or nonsurgical treatment options are available. Fetal goiter (FG) and fetal thyroid masses are rare fetal conditions and may occur as part of a hypothyroid, hyperthyroid, or euthyroid state. Screening for FGs should be carried out in pregnancies of mothers with thyroid disease. If a FG is detected, a detailed US examination should be performed. Congenital high airway obstruction syndrome (CHAOS) is characterized by bilaterally enlarged lungs, flat or inverted diaphragms, dilated tracheobronchial tree, and massive ascites. It is usually a lethal abnormality. Fetuses with suspected CHAOS should be referred to a fetal medicine center able to perform ex utero intrapartum treatment (EXIT) delivery. Neck teratomas are associated with high mortality rates. Prenatal US diagnosis of cervical teratoma can be made at 15 and 16 weeks of gestation. Planning of delivery in a tertiary center allows the performance of EXIT. Lymphangioma of the neck usually diagnosed in late pregnancy could be traditionally referred to as CH, but there is a different prenatal history and outcome.How to cite this articleVladareanu R, Vladareanu S, Berceanu C. Neck. Donald School J Ultrasound Obstet Gynecol 2016;10(3): 256-270.