The introduction of the cotton dye Congo red was a great step forward in the identification of amyloid [32]. The dye was synthesized in 1883 for the textile industry, and there is evidence that its name has a firm connection with a political conference, held in Berlin in 1884–1885, where the colonial powers discussed Central Africa; thus, the name has nothing to do with the origin of the dye [33]. Congo red was introduced as an intravenous test for systemic amyloidosis in patients, since deposits in the tissues bound the dye, and enhanced plasma clearance was taken as a sign of disease [34]. A quite substantial amount of Congo red was injected, often more than 10 ml of a 1 % aqueous solution of the dye [35]. Although unreliable and potentially dangerous, this test seems to have continued in use until the 1970s [36, 37]. This can seem surprising to us now, when some laboratories hesitate to utilize Congo red in histopathology due to its potential to be carcinogenic [38]. As early as 1884, the dye was tested as a histological stain [39], but it was not until 1927 that its properties as an amyloid stain were described [26]. At that time, a very important property of amyloid stained with Congo red was identified: namely, the enhanced birefringence of amyloid in tissue sections viewed under polarized light [26]. In fact, this technique is still used in diagnostic work throughout the world. Diagnostic biopsies from organs showing symptoms had been used for some time (for examples and references, see [40]), but it was not until 1960 that the well-known rectal biopsy was introduced as a diagnostic tool for systemic amyloidosis [41]. This was a most important advance, since before 1950, only 7 % of patients were diagnosed before death [42]. The technique most commonly used today, biopsy from subcutaneous fat tissue, was developed a decade later in the 1970s [43]. Since then, biopsy techniques have been further expanded to include determination of the biochemical nature of an amyloid deposit; today, this is considered to be a necessary step in the clinical handling of patients with systemic amyloidosis. Although a biopsy with microscopic demonstration of amyloid is still the only way to obtain a diagnosis, a method for visualizing amyloid in vivo based on the ubiquitously present serum amyloid P (SAP) component has been successfully developed [44].