An overview of constantly enlarging spectrum of renal lesions in monoclonal gammapathies and new insights in possible pathogenesis of renal disturbances is given. Between the different types of renal affections a predominant role is played by the "myeloma kidney", induced by the presence of casts, primary amyloidosis with light chains deposition and tubular dysfunctions. Case stories of 3 patients, affected by myeloma kidney (with acute and chronic renal failure) and primary amyloidosis (with pronounced nephrotic syndrome) in context of monoclonal gammapathy are presented. Clinical problems of patients necessitating intensive hematologic and nephrologic care are highlighted, as well as need of early diagnosis and complex care.