The renal biopsy plays an important role in the clinical evaluation of patients with lupus erythematosus. From numerous studies of renal biopsies in lupus nephritis, it has become clear that although the renal lesions are quite varied, the pattern of renal involvement correlates with the clinical outcome. The broad spectrum of lesions seen in lupus nephritis has been attributed to individual differences in the immune response in different patients or in the same patient during the course of disease. Classification of lupus nephritis authorized by the World Health Organization has provided a standardized approach to the findings on renal biopsy. This classification combines all of the morphologic modalities of biopsy interpretation including light, immunofluorescence, and electron microscopy as well as providing a semiquantitative assessment of activity and chronicity. The clinical correlations utilizing this histologic classifications have demonstrated that the specific nature of the renal histopathology can predict both the acute and long-term outcome of the renal disease in patients with lupus erythematosus and can be useful in determining the management of individual patients.