This study investigated nm23 protein expression in renal cell carcinomas to determine the relationship between nm23 protein expression and grade, stage, prognosis and the cell type. 89 cases were examined by immunohistochemistry. Tubular epithelia were homogeneously stained. Cytoplasmic nm23 protein levels were reduced in renal cell carcinoma. nm23 protein levels persisted in oncocytomas, which are accepted to be benign. Cytoplasmic nm23 staining intensity did not show any correlation with stage and grade of tumor nor prognosis. Reduction in nm23 protein levels may have a role during renal cell carcinoma pathogenesis but not in progression or metastasis suppression.