Renal impairment is a common phenomenon in myeloma patients. Pathogenesis is mainly based on the presence of monoclonal paraprotein but may include myeloma-independent mechanisms as well. There are various forms of paraprotein-related renal impairment. The majority of severe cases are due to cast nephropathy where precipitation on the basis of monoclonal free light chains causes complex tubular damage. Cast nephropathy requires quick diagnosis and specific treatment. Renal impairment increases mortality in myeloma patients. A quick and sustained response to treatment is crucial for preventing long-term dialysis dependence. Apart from preventing or treating other conditions endangering kidney function, an effective antimyeloma treatment is the mainstay of therapy. Available data are limited but novel substances added considerable efficacy to preexisting treatment concepts. Bortezomib gained importance due to its rapid action and missing nephrotoxicity, but also immunmodulatory substances such as lenalidomide were shown to restore kidney function. Cytostatic substances such as cyclophosphamide, bendamustine, and doxorubicin remain valuable combination partners for novel substances in order to achieve significant tumor responses. Extracorporeal removal of free light chains by plasmapheresis or extended daily high cut-off hemodialysis, if available, may further optimize management of acute myeloma-related renal failure.