This chapter highlights the significance of oxidative stress and vascular inflammation in promoting endothelial disease and atherosclerosis in sleep apnea patients, with an emphasis on the contribution of these mechanisms to the development of cardiovascular morbidity and stroke in these patients. Most studies investigating oxidative stress in patients with obstructive sleep apnea (OSA) present indirect findings by using various bodily fluid markers such as plasma, serum, or urine. The presence of IH is a key factor in initiating proatherogenic activity and a likely link for the close association between OSA and cardiovascular diseases. Increased oxidative stress, vascular inflammation, and endothelial dysfunction resulting from intermittent hypoxia (IH) can lead to high susceptibility of patients with OSA to stroke. The balance between proatherogenic and protective mechanisms may determine the predisposition of OSA patients to stroke or other cardiocerebrovascular diseases.