Obstructive sleep apnea syndrome (OSAS) is characterized with recurrent collapse of upper airway during sleep and resulted in hypoxia and sleep fragmentation. Several systemic and cardiovascular complications have been attributed to OSAS, which is caused by hypoxia and bursts of sympathetic activity. Increase of inflammatory mediators, which included C-reactive protein, oxidative stress, adhesion molecules, vascular endothelial growth factor and proinflammatory cytokines, were thought to involve in the developments of cardiovascular diseases in patients with OSAS. In our preliminary study, both serum levels of IL-6 and CRP were higher in patients with OSAS than control subjects, and the levels were inversely correlated with the lowest pulse oxygen saturation. Factors triggering inflammatory cascades in OSAS included hypoxia and sympathetic hyperactivity.