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Background: Despite advances in medical therapy, heart attack and stroke remain leading causes of morbidity and mortality. Biological, epidemiological, and clinical studies have shown that many patients (up to 33% in some trials) still have residual inflammatory risk that is associated with plaque rupture, even in the setting of low LDL. Methods and Results: In this study, we analyzed the T cell landscape of coronary atherosclerotic plaque to determine their role in the development of atherosclerosis and its adverse sequelae. We recruited 17 patients undergoing heart transplantation. From each explanted heart, we obtained plaques from the major coronary arteries, digested them to form a single cell suspension, sorted the arteries for CD4 and CD8 T cells into 96 well plates, and submitted them for single cell genotyping and phenotyping ( Figure 1 ). Although peripheral blood from these patients also contains T cell clones, plaque CD8 T cell clones appear to function differently than blood (e.g., producing more BCL6, TNF-, and interferon gamma) further supporting that this is not a bystander effect. We found CD4 and CD8 T cells with identical TCR sequence across the arteries of the same patient, suggesting CD8T cells are purposely recruited to the plaques. When we analyzed the percent clonality based upon location and disease severity, we find that clonality is not dependent on location and is present at all severity levels, especially, in early disease (e.g., AHA Type I-IV lesions. Conclusion: CD8 T cells are clonally expanded in atherosclerotic plaque and appear to function differently than blood, suggesting these cells are purposefully recruited.