Beckwith-Wiedemann syndrome (BWS), though a well-delineated clinical and morphological entity, can be difficult to diagnose by prenatal ultrasound examination when incomplete forms occur. We present a case with sonographic results including hydronephrosis, cardiomegalia, hepatomegalia, macroglossia, and prominent forehead. No abdominal wall defect was detected. Karyotype was normal. In spite of intensive prenatal diagnostics, BWS could not be diagnosed definitely until birth.