Radionuclide renal studies are particularly well suited to pediatrics as renal problems in children usually are part of a dynamic process which requires serial assessment. The absence of side-effects and the low radiation dose has added to their popularity in pediatrics. A number of different renal parameters can be evaluated using the appropriate radiopharmaceutical and method of analysis. The renal study is of value to assess patients with hydronephrosis both pre-operatively and for serial follow-up post-operatively, as well as to distinguish obstructive from non-obstructive uropathy. Perfusion to the kidney may be assessed and ischemic areas detected in children with hypertension or trauma. The renal scan commonly is used in patients with congenital anomalies such as ectopic and duplex kidneys, nonvisualized kidney on IVP and in children with oliguria or anuria secondary to diseases such as acute tubular necrosis, hemolytic uremic syndrome, and renal vein thrombosis. It frequently is done as an emergency procedure in neonates. In conjunction with the IVP and ultrasound, the renal study is useful in some cases of abdominal mass to distinguish between hydronephrosis, cystic kidneys and tumors.