Renal impairment is a common complication of multiple myeloma occuring in 50% of patients at some stage in their disease. Pathogenesis is multifactorial. Nephrotoxic manifestations of monoclonal immunoglobulin overexpression include the 'myeloma kidney', light chain deposition disease, AL amyloid, plasma cell infiltration and glomerulonephritis. Other factors, such as hypercalcaemia, hyperuricaemia, infection, hyperviscocity and nephrotoxic drugs can precipitate or exacerbate acute and chronic renal failure. Aggressive treatment has dramatically improved outcome in patients who present with acute or acute-on-chronic renal failure. Dialysis has become an accepted treatment acutely and in end stage renal disease due to myeloma. Conventional therapy with melphalan and prednisolone is still advocated for elderly patients. However, renal failure is not a contraindication to aggressive cytoreduction, stem cell collection, double hemibody radiotherapy and autologous transplantation in those otherwise fit to tolerate these procedures. Prognosis is primarily determined by the response of the myeloma clone to chemotherapy. Outcome in chemosensitive patients approaches that of patients with equivalent disease stage without renal dysfunction.