The objective of this chapter is to provide a brief but comprehensive review of the pathologic features of renal disease in the native and transplanted kidney. A brief introduction describes the technical aspects of renal biopsy processing for pathologic examination. The main pathologic characteristics of light microscopy, immunofluorescence/immunohistochemistry, and electron microscopy are described for different glomerulopathies and for tubulointerstitial and vascular diseases in the native kidney, including minimal change disease, glomerular tip lesion, focal segmental glomerulosclerosism, membranous nephropathy, membranoproliferative glomerulonephritis, diabetes, hypertension, thrombotic microangiopathy, and renal disease associated with paraproteins and plasma cell dyscrasias. A separate section deals with the pathology of the renal allograft. Tables are included with summaries of current classification schemes for selected diseases.