Background: Obstructive sleep apnea (OSA) is a disease characterized by periodic upper airway collapse during sleep, which could result in either apnea, hypopnea or both. OSA is very often undetected but it is strongly associated with variety of medical complication, among others cardiovascular diseases.Purpose: To inform ENT specialists about the pathogenesis and pathophysiology of OSA and its complications. Literature review: Recent data from several studies has documented the association between OSA and cardiovascular disorders such as hypertension, heart failure, arrhytmia and atherosclerosis. The undetectable cardiovascular complication that lead by OSA could make the management of cardiovascular disorders uneffective. Conclusion: A good understanding can help physicians to diagnose, manage and prevent cardiovascular complication that caused by OSA.