Transthyretin (TTR)-related familial amyloidotic polyneuropathy (FAP) is an autosomal dominant form of fatal hereditary amyloidosis. Until 25 years ago, tools for diagnosis of FAP were restricted to clinical manifestations and pathologic methods, and a small number of patients in the restricted endemic areas could be diagnosed with this disease. However, owing to progress in biochemical and molecular genetic analyses, this disease is now believed to occur worldwide. As of today, reports of about 100 different points of single or double mutations, or a deletion in the TTR gene have been published, and several different phenotypes of FAP have been documented, even for the same mutation in the TTR gene. Since liver transplantation has been established to halt the progression of FAP, rapid and reliable diagnostic system for FAP is needed. We present here a new diagnostic procedure for the disease using current methods of molecular genetics and protein chemistry.