The official journal of the Japan Atherosclerosis Society and the Asian Pacific Society of Atherosclerosis and Vascular Diseases Review Lipoprotein(a) [Lp(a)], discovered in 1963, has been associated with atherosclerotic cardiovascular disease (ASCVD) independent of other traditional risk factors, including LDL cholesterol. Lp(a) is an apolipoprotein B (apoB)-containing lipoprotein, which contains an LDL-like particle. Unlike LDL, which is a primary therapeutic target to decrease ASCVD, current guidelines recommend measuring Lp(a) for risk assessments because there is no clear evidence demonstrating the clinical benefit of decreasing Lp(a) using classical drugs such as niacin. However, recent Mendelian randomization studies indicate that Lp(a) causally correlates with ASCVD. In addition, novel drugs, including PCSK9 inhibitors, as well as antisense oligonucleotide for apo(a), have exhibited efficacy in decreasing Lp(a) substantially, invigorating a discussion whether Lp(a) could be a novel therapeutic target for further ASCVD risk reduction. This review aims to provide current understanding, and future perspectives, of Lp(a), which is currently considered a mere biomarker but may emerge as a novel therapeutic target in future clinical settings. This review aims to provide a current understanding, and future perspectives, of Lp(a), which is currently considered a mere biomarker but may emerge as a novel therapeutic target in future clinical settings. What is Lp(a)? Lp(a) is a particle containing two different elements (Fig. 1). The first element is an LDL-like particle containing an apoB-100 particle, which is insoluble in water. Reportedly, the LDL-like particle in Lp(a) is larger in size and higher in lipid content, with a density marginally lower than the LDL particle isolated from the same individual 11). The second element is a hydrophilic glycoprotein called apo(a) that shares homology with plasminogen, giving the particle atherogenic properties. Plasminogen has five kringles (KI-KV); apo(a) does not contain KI-KIII but has 10 subtypes of KIV (with KIV1, and KIV3-KIV10 have one copy, and KIV2 has one to 40 copies), and one copy of KV. The apo(a) isoform size and the Lp(a)