Our understanding of the morphologic and genetic features of renal epithelial neoplasia has brought about profound changes in the classification of these tumors. It is clear that they represent a heterogeneous group of tumors with distinct histopathologic, genetic, and clinical features ranging from benign to high-grade malignant. "Granular" and "sarcomatoid" carcinomas are not distinct entities, since tumors with granular or spindle cell features may be seen in many tumor-types. Using conventional pathologic tools such as hematoxylin and eosin staining, histochemistry, immunohistochemistry, and electron microscopy, we are able to properly classify the majority of these tumors. Nevertheless, approximately 6% to 7% of cases are impossible to classify in this fashion, thus requiring molecular genetic studies for proper characterization.