Although the pathogenesis of asthma is incompletely understood, studies have shown that it is associated airway inflammation and a state of increased free radical formation, because cells derived from airways and peripheral blood of patients with asthma generate increased amount of reactive oxygen species, the level of which is related to severity of asthma. Recent preliminary studies have indicated that, apart from the presence of chronic airway inflammation, asthma may also be associated with chronic low grade systemic inflammation and increased oxidative stress. Intuitively, this asthma-related systemic inflammation may increase the risk for development of cardiovascular and cerebrovascular diseases.