The article reviews the role of reactive oxygen species (ROS) in cardiovascular dysfunction associated with diseases such as hyperlipidemia, diabetes mellitus, hypertension, ischemic heart disease, and chronic heart failure. ROS, primarily produced by vascular cells including endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts, have distinct functional effects on each cell type, including cell growth, apoptosis, migration, inflammatory gene expression, and matrix regulation. The review focuses on the effects of ROS on endothelial and smooth muscle cells, highlighting their roles in endothelium-dependent vasorelaxation, apoptosis, adhesion molecule expression, angiogenesis, smooth muscle cell growth and migration, matrix remodeling, and inflammatory gene expression. The clinical implications of oxidative stress are also discussed, including its role in atherosclerosis, hypertension, diabetes mellitus, and restenosis after angioplasty. Despite extensive research, the clinical benefits of antioxidant administration have been limited, and further studies are needed to optimize the use of antioxidants in cardiovascular disease prevention and treatment.The article reviews the role of reactive oxygen species (ROS) in cardiovascular dysfunction associated with diseases such as hyperlipidemia, diabetes mellitus, hypertension, ischemic heart disease, and chronic heart failure. ROS, primarily produced by vascular cells including endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts, have distinct functional effects on each cell type, including cell growth, apoptosis, migration, inflammatory gene expression, and matrix regulation. The review focuses on the effects of ROS on endothelial and smooth muscle cells, highlighting their roles in endothelium-dependent vasorelaxation, apoptosis, adhesion molecule expression, angiogenesis, smooth muscle cell growth and migration, matrix remodeling, and inflammatory gene expression. The clinical implications of oxidative stress are also discussed, including its role in atherosclerosis, hypertension, diabetes mellitus, and restenosis after angioplasty. Despite extensive research, the clinical benefits of antioxidant administration have been limited, and further studies are needed to optimize the use of antioxidants in cardiovascular disease prevention and treatment.