Beta-catenin is a glicoprotein which has an important role in cell-cell adhesion, as well as in cell signal transmission, in u regulation of gen expression and in interaction with axin and APC (adenomatous poliposis coli). Its oncogenic role in several types of carcinomas in human population is well known. It is very likely that beta-catenin as an protooncogen plays an important role in genesis of Wilms tumor. It is well known that in 15% Wilms tumors there are beta-catenin mutations, which indicates that there is a disorder in Wnt signal path that plays an important role in Wilms tumor genesis. The aim of our study was to investigate b-catenin expression in Wilms tumor, to compare it with the expression in normal renal tissue as well as to see if there is a positive correlation between b-catenin expression in Wilms tumor with tumor stage, histologic type and/or prognostic group.