The purpose of this series is to describe the grayscale and color Doppler sonographic characteristics as well as the histopathologic features of rare solid posterior neck masses identified on prenatal sonography in pregnant patients. We conducted a retrospective review of detailed fetal sonographic examinations of second- and third-trimester pregnancies referred to the Center for Fetal Diagnosis and Treatment at the Children's Hospital of Philadelphia for suspected fetal neck masses from June 1998 to December 2011. Eight predominately solid posterior neck masses were identified on 139 studies performed during the study period. Of the 7 cases in which follow-up was available, 6 were confirmed as hemangiomas, and 1 was confirmed as a kaposiform hemangioendothelioma with Kasabach-Merritt syndrome. The most common sonographic features were hypervascularity (7) and calcifications (5). Posterior solid fetal neck masses are rare anomalies. Hemangioma is the most common etiology and should be suggested as the likely diagnosis rather than teratoma, even in the presence of calcifications.