Covering: 1989 to September 2010 The spirodioxynaphthalenes are a group of fungal secondary metabolites, consisting of a 1,8-dihydroxynaphthalene-derived spiroketal unit linked to a second oxidized naphthalene moiety, that show a great variety of biological activities. This review summarizes the research on the isolation, structure elucidation, biological activities, biosynthesis, and chemical synthesis of the spirodioxynaphthalenes published over the last 20 years. More than 100 fungal and plant metabolites are described, and over 100 references cited.