An attempt has been made to classify the numerous drugs used to treat cognition deficits according to their chemical structures and to their main physiological effects. Particular emphasis has been given to the following families: Piracetam-type, Co-dergocrine-type and vincamine-type compounds; cholinergic agents, psychostimulants, vasodilators, antianoxic agents, peptides, growth factors and gangliosides. Compounds described in the scientific literature and in patents are presented. Reference has been made to preclinical and clinical studies (973 quotations from original articles, 100 quotations of reviews and books).