Amyloidosis is a heterogeneous group of diseases in which an otherwise normal protein, with or without proteolytic cleavage, forms insoluble amyloid fibrils. These, in turn, deposit in various organs and cause dysfunction. A wide range of diseases are associated with amyloidosis such as Alzheimer's disease, multiple myeloma, other plasma cell disorders, and chronic inflammation, either as a cause, or result, of amyloid production. This heterogeneity in cause and presentation leads to an incomplete understanding of the pathophysiology of amyloid disease. As such, study of this complicated disease process presents significant challenges. The purpose of this review article is to introduce the biochemistry of amyloidosis including ultrastructure analysis, models of monomer aggregation, the importance of the amyloid microenvironment, and the mechanisms of organ dysfunction, including the role of "toxic intermediates." Pathophysiologic analysis of amyloidosis will focus on diagnostic tools as well as the classification of the various forms of amyloidosis. Finally, treatment of amyloidosis will be reviewed including traditional and established modalities. We will also introduce new and novel treatment options as they relate to the basic pathophysiology of this complex and heterogeneous disorder.