‘Wilms’ tumor’ is the most common renal tumor in children. Treatment as well as definition of nephroblastoma also has had a progressive history. Wilms’ tumor (WT) is a malignant embryonal tumor of the kidney and the second most common malignant retroperitoneal tumor. It is the most common primary renal tumor of childhood. In spite of the improvement of recent knowledge regarding Wilms’ tumor the exact etiology of its development remains unclear. Wilms’ tumor is recognized as an embryonal renal neoplasm in which blastemal, stromal and epithelial cell types are present. It has been postulated that these blastemal elements or nephroblastomatosis may be the precursors of Wilms’ tumor. The development of oncogenesis appears to occur through hamartomas, which may become blastemic tumorlets, which may then in turn colonize to produce a Wilms’ tumor.