Over the last decade, significant data has accumulated to suggest that biomarkers of oxidative stress accurately reflect the presence of cardiovascular risk factors, the extent of cardiovascular disease (CVD), and cardiovascular outcomes. This cumulative evidence has supported the approval of several of these biomarkers for clinical applications. For example, lipoprotein-associated phospholipase A(2) (Lp-PLA2) and myeloperoxidase (MPO) mass assays are now available to assist clinicians in determining overall cardiovascular risk in asymptomatic patients thought to be at increased risk or in patients with cardiovascular symptoms. However, it is not yet firmly established whether and to what extent these oxidative biomarkers reflect changes in response to therapeutic interventions. This article reviews the latest data on MPO, isoprostanes, oxidized low-density lipoprotein, oxidized phospholipids, and Lp-PLA2 biomarker assays, and it assesses their role in reflecting therapeutic interventions to treat CVD.