Oxidative response regulates many physiological response in human health, but if not properly regulated it could also lead to a number of deleterious effects. The importance of oxidative stress injury depends on the molecular target, the severity of the stress, and the mechanism by which the oxidative stress is imposed: it has been implicated in several diseases including cancer, neurodegenerative diseases, malaria, rheumatoid arthritis and cardiovascular and kidney disease. Most of the common diseases, such as hypertension, atherosclerosis, heart failure, and renal dysfunction, are associated with vascular functional and structural alterations including endothelial dysfunction, altered contractility, and vascular remodeling. Common to these processes is increased bioavailability of reactive oxygen species (ROS), decreased nitric oxide (NO) levels, and reduced antioxidant capacity. Oxidative processes are up-regulated also in patients with chronic renal failure (CRF) and seem to be a cause of elevated risk of morbidity and mortality in these patients. In this review, we highlight the role of oxidative stress in cardiovascular and renal disease.