Renal ultrasonography (USG) has become a primary investigation along with renal biochemistry in renal failure. An early USG evaluation can identify an acute renal failure from a chronic renal failure or an obstructive renal failure from non-obstructive renal failure. These findings can help to plan treatment and prognosticate the course of the renal failure. For example, identification of a small kidney can suggest a chronic renal failure, to plan for a continuous ambulatory peritoneal dialysis and prognosticate to the parents the need for long-term dialysis and transplant. Identification of obstruction can decide for a surgical intervention and save the child from dialysis and its costs. Normal kidney in USG has a central white or echogenic area surrounded by a cortex which is a varying shade of grey.