Background: Beckwith-Wiedemann syndrome (BWS) is a rare disorder characterized by macrosomia, macroglossia, visceromegaly, and omphalocele and an increased risk of growing tumors. Prenatal and postnatal high levels of serum alpha-fetoprotein are associated with several diseases and neoplasms including hepatoblastomas and other hepatic tumors. The diagnosis of BWS is usually made in the postnatal period on the basis of physical exam features and hypermethylation of the H19 gene., Case: A 30-year-old woman gravida 3, para 2, underwent maternal serum screening at 15 weeks' gestation. The screening was negative for Down's syn drome (risk 1/6085), but positive for NTDs. Further ultrasound examination at 20 and 30 weeks' evidenced a fetal overgrowth and a 3-D scan at 33 weeks' gestation presented a protruding tongue, and a fixed opened mouth caused by macroglossia., Conclusions: BWS was suspected on the basis of clinical features, and molecular analysis of critical region 11p15.5 revealing the hypermethylation of H19 gene supported the diagnosis.