The limited distribution of lipoprotein (a) (Lp(a)) to humans, Old World primates and to the European hedgehog, has raised considerable interest and speculation regarding its possible physiological role. Lp(a) has variable circulating concentrations (<0.1 – >100 mg/ml) which are highly genetically determined in humans. These characteristics gave rise to several theories concerning the origins and evolution of Lp(a). Lp(a) has a protective role after injury since Lp(a) particles bind to macrophages and platelets membrane receptors, leading to fibrin activation and injury healing. On the other hand, Lp(a) seems to be implicated in the formation of atheromatic plaques but also in cerebrovascular events and stenosis of the aortic valve.The main genetic factor determining plasma Lp(a) levels is the Lp(a) gene (LPA). Most Caucasian people have normal plasma Lp(a) concentrations, but there is important distribution variation according to race. Women seem to have increased Lp(a) levels compared with men, while diabetes mellitus type 2 favours lower plasma Lp(a) levels. Nutrition, hormones and several drugs may also influence circulating Lp(a) levels.