Besides bone pain, pathologic fractures, anaemia, and recurrent infectious diseases, renal failure is one of the most serious complications in multiple myeloma patients. Its incidence is generally underestimated because of the low reliability of the parameters routinely used for the evaluation of renal dysfunction. Other laboratory tests in the literature are reported to be more suitable to better define the extension of the renal impairment, namely urinary proteins or creatinine clearance. We here report on the clinical implication of urinary parameters in defining the renal function in myeloma patients.