Acute renal failure (ARF) is common problem in pediatrics which continues to have a poor prognosis despite advances in renal replacement therapy. When one considers the future field of acute renal failure, the renal biopsy would be considered as the most important diagnostic modality because most of important therapeutic issues depend on a modern understanding the pathology of acute renal failure. A biopsy provides a definitive diagnosis and alter the management of acute renal failure.The aim of this study is to evaluate the value of renal biopsy in diagnosing the etiology of ARF, to give information about the most common cause of ARF in children and to correlate between the clinical diagnosis and pathological diagnosis and its impact on prognosis. The result of the biopsy had confirmed the clinical diagnosis in 47% of cases, altered the clinical diagnosis in 53% of cases and resulted in change the therapeutic management in 71%of cases.From the study, the renal biopsy provides clear guidelines which aid the diagnostic evaluation and subsequent proper management.