A polemic in response to de Kat Angelino et al (Clin Chem, 2010, 56, 1188-90) is given. Mead and Carr-Smith agree that nephelometric measurement of monoclonal polymerized free light chains (FLCs) cannot be consistently accurate, there are now >200 publications attesting to the clin. value of these assays. However, if alternative assay formats were to be considered for clin. use, confirmation of their utility would be required.