Epidemiological and clinical studies over the past decade have firmly established that elevated plasma concentrations of lipoprotein(a) (Lp(a)) are an important, independent and probably causal risk factor for the development of cardiovascular diseases. Whereas a link between Lp(a) levels and atherosclerotic cardiovascular disease (ASCVD) has been appreciated for decades, the role of Lp(a) in calcific aortic valve disease (CAVD) and aortic stenosis has come into focus only in the past 5 years. ASCVD and CAVD are aetiologically distinct but have several risk factors in common and similar pathological processes at the cellular and molecular levels. Oxidized phospholipids, which modify Lp(a) primarily by covalent binding to its unique apolipoprotein(a) (apo(a)) component, might hold the key to Lp(a) pathogenicity and provide a mechanistic link between ASCVD and CAVD. Oxidized phospholipids colocalize with apo(a)-Lp(a) in arterial and aortic valve lesions and directly participate in the pathogenesis of these disorders by promoting endothelial dysfunction, lipid deposition, inflammation and osteogenic differentiation, leading to calcification. The advent of potent Lp(a)-lowering therapies provides the opportunity to address directly the causality of Lp(a) in ASCVD and CAVD and, more importantly, to provide both a novel approach to reduce the residual risk of ASCVD and a long-sought medical treatment for CAVD.