Context.— Congenital mature teratomas of the umbilical cord are extremely rare and pose a challenge in prenatal diagnosis. Mature teratomas are defined as tumors composed of mature tissues derived from more than 1 germ cell layer. The tumor often shows solid and cystic components, which adds to the difficulty of prenatal diagnosis. Although benign, mature teratomas of the umbilical cord are commonly associated with congenital malformations of the fetus with variable severity and rarely, with chromosomal abnormalities. Objective.— To review the clinical, radiologic, gross, and histologic features of umbilical cord teratoma; its differential diagnosis; and to emphasize the increased risk of associated congenital malformations. Data Sources.— Umbilical cord teratoma cases published in the literature. Conclusions.— Umbilical cord teratomas are difficult to diagnose by imaging studies alone and require histopathologic examination for diagnosis. Given the increased risk of associated anomalies and malformations, the finding of umbilical cord teratoma should trigger a detailed and comprehensive evaluation of the neonate for additional abnormalities.