Bence-Jones proteinuria consists in monoclonal light chains into the urine. Normally kidney eliminates light chains but, when light chains are in excess, they make histological and functional lesion to tubules, glomerulus and vessels both by direct action, or lysosomal enzyme releasing or making tubular obstruction. We analyse these kidney's damages from the morphological and functional point of view. Bence-Jones proteinuria can be detected by urinary protein electrophoresis, immunoelectrophoresis, immunofixation electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional electrophoresis and capillary electrophoresis.