Lp(a) is a lipoprotein present in all individuals in concentrations that are genetically determined. Its structure is characterized by the presence of an apoprotein with a high carbohydrate content called apoprotein a. Since 1972, numerous concordant data have endowed Lp(a) with a high risk of atherogenesis. This risk applies to the coronary and cervico-encephalic arteries. For the latter, Lp(a) even is a lipid parameter regarded as a major risk factor. The origin and metabolism of Lp(a) are little known, by they seem to differ from those of low-density lipoproteins. Its specific apoprotein of Lp(a). At the moment, there is no simple dietetic or medicinal treatment that can lower substantially the serum level of Lp(a).