Lipoprotein(a) was discovered by chance by Berg in 1963; after twenty years of research, the chemical, physical and metabolic characteristics of Lp(a) are now known. This lipoprotein forms the missing link between the lipid metabolism and the coagulation-fibrinolysis process. The A. describe its similarity to plasminogen, its capacity to delay coagulum or embolus destruction and highlight its structural and functional similarity to lipid metabolism. To day, a total of 6 Lp(a) isoforms have been identified with different molecular weights: in addition, the inverse proportion between the isoforms' molecular weight and Lp(a) plasma concentration has been demonstrated. Lp(a) is not the product of the metabolism of other lipoproteins nor is it a catabolite of LDL; it is produced ex-novo and does not apparently exchange its proteic fraction with other lipoproteins. The paper also examines the question of whether Lp(a) is a plasma marker which increases during the formation of atherosclerotic plaque or whether it should not be considered an atherogenetic factor. To this end the possible mechanisms by which Lp(a) is deposited in plaque are examined. Lastly, the paper reviews all studies concerning the relationship between Lp(a), ischemic cardiopathy and cerebrovascular disease.