In spite of success of modern pediatric oncology, cases in which we are not able to reach the prospective affirmative effect of performed therapy are still observed. The purpose of our study was to examine the expression of WT1 gene product and CD44 adhesive molecule in nephroblastoma histologic types - one of the currently used prognostic marker for this group of tumor. We found correlations between CD44 expression and histologic type of tumor. We suppose that high CD44 expression in nephroblastoma group of tumors may confirm their high malignant potential. Expression of the WT1 gene product we found in all the investigated tumor tissue samples. However we did not found statistically significant correlations between WT1 expression and histologic type of the tumor and there was no correlation between CD44 and WT1 expression in blastemal nor of epithelial component of nephroblastoma in our study. Lack of this correlation also permits to suppose that the high activity is an integral feature of all Wilms tumor cells and is not only characteristic for anaplastic and blastemal nephroblastomas.