Many different types of benign and malignant tumors have been reported in the kidney. Renal cell neoplasms, derived from the renal tubular epithelial cells, are the most common renal tumors. They have distinct clinical, pathologic, and genetic characteristics as well as diverse prognosis and therapeutic responses. The 2004 World Health Organization classification of renal tumors represents the most updated classification system based primarily on morphological features. Genetic characteristics have been increasingly incorporated into the clinically meaningful classification systems. Pathological examination of the renal neoplasm specimens not only renders an accurate diagnosis and classification but also provides information important for prognosis and therapeutic decisions.