The biogenesis and degradation/clearance of Abeta amyloid lies at the centre of the pathogenesis of Alzheimer's disease. Quantification of the various metabolic pools of Abeta in the brains and in the periphery may aid in diagnosis, prognosis and the elucidation of the natural history of this disorder. Estimation of the Abeta levels using immunoassays (ELISA and the western blots) are complementary techniques which are now being applied in humans and experimental models. The various forms of Abeta in differing cellular compartments are now being assayed, and a picture of the natural history of Alzheimer's disease is beginning to emerge.