Introduction: Measurement of lipoprotein(a) [Lp(a)] is recommended once in a lifetime to identify individuals at high risk of atherosclerotic cardiovascular disease (ASCVD). We aimed to analyze the clinical features of patients with extreme Lp(a). Methods: Cross-sectional, case-control study of a single healthcare organization between 2015 and 2021. Individuals with extreme Lp(a) > 430 nmol/L (53 of 3900 tested patients) were compared to age- and sex-matched controls with normal range Lp(a). Results: Mean patient age was 58 ± 14 years (49% women). Myocardial infarction (47.2% vs. 18.9%), coronary artery disease (CAD) (62.3% vs. 28.3%), and peripheral artery disease (PAD) or stroke (22.6% vs. 11.3%) were more prevalent in patients with extreme than normal range Lp(a). The adjusted odds ratio [95% confidence interval (CI)] associated with extreme compared to normal range Lp(a) was 2.50 (1.20–5.21) for myocardial infarction, 2.20 (1.20–4.05) for CAD, and 2.75 (0.88–8.64) for PAD or stroke. A high-intensity statin plus ezetimibe combination was issued by 33% and 20% of CAD patients with extreme and normal range Lp(a), respectively. In patients with CAD, low density lipoprotein cholesterol (LDL-C)