Monocytes play a critical role in the development and progression of atherosclerosis, a chronic inflammatory disease that is the leading cause of cardiovascular disease. Monocytes, a heterogeneous population of circulating cells, are recruited to atherosclerotic plaques where they differentiate into macrophages and foam cells, contributing to plaque formation and instability. The recruitment and function of monocytes are influenced by various factors, including chemokine receptors such as CCR2, CX3CR1, and CCR5, as well as adhesion molecules like selectins and integrins. Different subsets of monocytes, such as Gr1+Ly6C+ and Gr1-Ly6C-low, have distinct roles in atherosclerosis, with Gr1+Ly6C+ monocytes being more involved in inflammatory responses, while Gr1-Ly6C-low monocytes may patrol blood vessels and contribute to early atherogenesis. Monocytes can also emigrate from plaques, potentially aiding in plaque regression. The heterogeneity of monocytes and their ability to differentiate into various cell types, including macrophages and dendritic cells, underscores their complex role in atherosclerosis. Understanding the mechanisms of monocyte recruitment, function, and heterogeneity is essential for developing targeted therapies for atherosclerosis. Research continues to explore the interactions between monocytes and other immune cells within plaques, as well as the impact of monocyte subsets on plaque stability and vulnerability. The study of monocyte biology in atherosclerosis is crucial for advancing our understanding of the disease and improving treatment strategies.Monocytes play a critical role in the development and progression of atherosclerosis, a chronic inflammatory disease that is the leading cause of cardiovascular disease. Monocytes, a heterogeneous population of circulating cells, are recruited to atherosclerotic plaques where they differentiate into macrophages and foam cells, contributing to plaque formation and instability. The recruitment and function of monocytes are influenced by various factors, including chemokine receptors such as CCR2, CX3CR1, and CCR5, as well as adhesion molecules like selectins and integrins. Different subsets of monocytes, such as Gr1+Ly6C+ and Gr1-Ly6C-low, have distinct roles in atherosclerosis, with Gr1+Ly6C+ monocytes being more involved in inflammatory responses, while Gr1-Ly6C-low monocytes may patrol blood vessels and contribute to early atherogenesis. Monocytes can also emigrate from plaques, potentially aiding in plaque regression. The heterogeneity of monocytes and their ability to differentiate into various cell types, including macrophages and dendritic cells, underscores their complex role in atherosclerosis. Understanding the mechanisms of monocyte recruitment, function, and heterogeneity is essential for developing targeted therapies for atherosclerosis. Research continues to explore the interactions between monocytes and other immune cells within plaques, as well as the impact of monocyte subsets on plaque stability and vulnerability. The study of monocyte biology in atherosclerosis is crucial for advancing our understanding of the disease and improving treatment strategies.