The authors present a case of Waldenström's macroglobulinemia (WM) associated with generalized amyloidosis of amyloid-A type. A 77-year-old man with a 25-year history of degenerative joint disease and a 13-year history of WM died of multisystemic failure. At autopsy, generalized and severe amyloid deposits were detected. Special conventional stains and immunohistochemical examination revealed amyloid-A de posits, which are extinguishingly rare in WM. This is probably related to the disease being chronic, which results in excessive production of precursor protein. The detection of amyloid-A type fibrils was possible only through the application of the immunohis tochemical procedure. The authors emphasize using the immunohistochemical typing of amyloid deposits for the purpose of classification, therapy, and prognosis. Int J Surg Pathol 1 (2):123-128, 1993