Abstract Renal impairment is a common complication of multiple myeloma. Chronic renal failure is classified according to glomerular filtration rate as estimated by the MDRD (modification of diet in renal disease) formula, while RIFLE (risk, injury, failure, loss and end-stage renal disease) and AKIN (acute renal injury network) criteria may be used for the definition of the severity of acute renal injury. Novel criteria based on estimated glomerular filtration rate measurements are proposed for the definition of the reversibility of renal impairment. Renal complete response (CRrenal) is defined as sustained (i.e., lasting at least 2 months) improvement of creatinine clearance (CRCL) from under 50 mL/min at baseline to 60 mL/min or above. Renal partial response (PRrenal) is defined as sustained improvement of CRCL from under 15 mL/min at baseline to 30 to 59 mL/min. Renal minor response (MRrenal) is defined as sustained improvement of the baseline CRCL of under 15 mL/min to 15 to 29 mL/min or, if baseline CRCL was 15 to 29 mL/min, improvement to 30 to 59 mL/min. Bortezomib with high-dose dexamethasone is considered the treatment of choice for myeloma patients with renal impairment and improves renal function in most patients. Although there is limited experience with thalidomide, this agent can be administered at the standard dosage to patients with renal failure. Lenalidomide, when administered at reduced doses according to renal function, is effective and can reverse renal impairment in a subset of myeloma patients.