The renal manifestations in systemic lupus erythematosus (SLE) are protean and difficult to categorize into clinical syndromes and histologic classes. Lupus nephritis is frequently unrecognized until full-blown nephritic and/or nephrotic syndrome with renal failure emerge. Epidemiologically, approximately one third of SLE patients from unselected populations have renal involvement early during the disease. Most renal abnormalities emerge within the first few years of SLE diagnosis. Currently, most nephrologists agree that an early renal biopsy is worthwhile in those SLE patients with abnormal urinalysis and/or reduced renal function. First, it provides a histologic categorization of the glomerulonephritis as well as an assessment of the degree of activity and chronicity. Second, it provides vital prognostic information. Third, it is beneficial in planning a more rational therapy with or without potentially toxic immunosuppressive agents. Over the last 3 decades, many controlled clinical trials for treatment of lupus nephritis have been completed with a few therapeutic immunosuppressive regimens. Among those agents used. cyclophosphamide and azathioprine provide a reduction of morbidity in those patients afflicted with proliferative forms of lupus glomerulonephritis. A new immunosuppressive agent, mycophenolate mofetil, is being studied for treatment of proliferative forms of lupus glomerulonephritis in a controlled clinical trial at our institution. Immunosuppressive agents and the availability of dialysis and transplantation have improved the survival of patients with lupus nephritis, in particular those with proliferative forms.