An intrinsically disordered protein (IDP) is a protein in which the fixed or ordered three-dimensional structure is absent, generally when its macromolecular interaction partners, such as other proteins or RNA are absent. The flexible structure of these proteins allows them to accomplish their biological functions. IDPs play an important role in DNA regulation and cell signaling owing to their ability to participate in weak multivalent interactions that are highly cooperative and dynamic. There are various IDPs that can adopt a fixed three-dimensional structure after they bind themselves to other macromolecules. IDPs are associated with numerous diseases such as cancer, cardiovascular disease, amyloidoses, neurodegenerative diseases and diabetes. This book includes some of the vital pieces of works being conducted across the world, on various topics related to the relationship between intrinsically disordered proteins and diseases. Its extensive content provides the readers with a thorough understanding of the subject.