Cockroaches, commonly found in urban dwellings worldwide, have long been considered vectors of various infectious diseases and cockroach allergens are one of the major etiologic risk factors for IgE-mediated allergic respiratory illness throughout the world. A high prevalence of cockroach hypersensitivity in atopic (20-55 %) and asthmatic (49-60%) populations has been documented. Cockroach allergens with molecular weights ranging from 6 to 120 kD have been identified by various standard immunochemical techniques. This article covers the characteristics of major cockroach allergens that have been purified, sequenced, cloned, and produced as recombinant proteins.