More than 25 clinical settings in amyloidosis have been acknowledged in which a peculiar criminal protein, a precursor protein, has been identified. As of now, however, the mechanism of amyloidogenesis, by which a precursor protein is transformed irreversibly into an amyloid protein, remains to be clarified. We speculated that a study of the molecular conformation of beta 2-microglobulin (beta 2 m), a precursor protein in dialysis-related amyloidosis (DRA), might provide a typic model of amyloidogenesis in other precursor proteins. Therefore, we investigated the misfolding of beta 2 m in DRA using a specific monoclonal antibody against C-terminal peptide 92-99 of beta 2 m. Our study indicated the possibility that the monoclonal antibody specific for C-terminal 92-99 of beta 2 m can detect a pre-amyloid state in amyloidogenesis in vivo, which might take place in the extravascular space.