Several renal diseases are associated with the dysproteinemias, and their pathogenesis is related to paraprotein deposits in the kidney: light chains can affect the kidney by a direct toxic effect on tubular cells, or by intratubular or tissue precipitation. Multiple myeloma (MM) is the most prevalent dysproteinemia, and the spectrum of associated renal diseases includes myeloma kidney (cast nephropathy), amyloidosis and monoclonal immunoglobulin deposition disease (MIDD). Renal failure is seen in approximately 50% of patients with MM at diagnosis, most frequently attributed to myeloma kidney. Renal function can recover in more than half the patients by prompt rehydration with intravenous fluids, to achieve a urine flow of >3 l/day, and by treating the hypercalcemia. Plasma exchange in combination with corticosteroids is suggested in patients with rapidly progressive renal failure. When renal failure is associated with MIDD or amyloidosis, renal function recovery is reduced to 10%, and patient survival is related to the entity of extrarenal tissue distribution of paraprotein deposits. Dialysis should be offered to patients with end-stage renal disease. High dose chemotherapy and autologous stem cells transplantion (SCT) is recommended in patients who do not have severe co-morbidities.