Cystic fibrosis (CF) is a hereditary disease of exocrine gland function that involves multiple systems but chiefly results in chronic respiratory infections, the major cause of death, pancreatic enzyme deficiency and severe malnutrition, mostly in untreated patients. The association between CF and other inherited diseases or congenital anomalies is rare. We describe for the first time the association of CF and Beckwith-Wiedemann syndrome (BWS). BWS is a genetic disorder commonly characterized by overgrowth. The most common features of BWS include macrosomia, macroglossia, abdominal wall defects, an increased risk for childhood tumors, kidney abnormalities, hypoglycemia in the newborn period and unusual ear creases or pits.