Congenital heart disease in children is usually associated with congestive heart failure (CHF). The most effective medical treatment of CHF is diuretics. Prolonged use of furosemide is associated with hypercalciuria, nephrocalcinosis and renal calculi.This study included thirty patients with CHD receiving furosemide for more than 6 months. Thirty age and sex matched normal children were included as control group. The two studied groups were subjected to full history taking, general and local cardiac examination, laboratory investigations (CBC, serum Na, K, Ca, Ph, alkaline phosphatase, BUN, creatinine and calcium/creatinine ratio) and renal ultrasonography.Nephrocalcinosis was detected in 5 (16.7%) patients. Urinary calcium/creatinine ratio was higher than normal in one case only. In conclusion, prolonged furosemide therapy could induce nephrocalcinosis.Renal ultrasonography is a useful and non invasive method for nephrocalcinosis detection. Periodic renal ultrasonography is recommended for patients with prolonged furosemide therapy.