Erdheim-Chester Disease (ECD) is a rare form of non Langerhans' cell histiocytosis. The etiology of ECD is unknown yet. The disease is characterized by the infiltration of lipid-laden histiocytes with foamy to bones and various organs. The heterogeneous manifestations of ECD vary among different individuals. This results in a presentation that may vary from an indolent focal disease to a life threatening organ failure. This review focuses on the etiology, clinical presentation, diagnostic criteria and treatment of Erdheim-Chester disease (ECD).