Sleep Apnea Syndrome (SAS) is a common disorder and a major health hazard thataffects many body systems. It is particularly associated with increased cardiovascularmorbidity and mortality. Obstructive Sleep Apnea (OSA) and its cardiovascularconsequenceshave attracted considerable attention in recent years. The aim of this study was to assesstheeffects of apnea/hypopnea on 20 patients with coronary artery disease (CAD), (14males,6females and mean age 51+7.4 yr) including myocardial infarction MI in 10, unstableanginaUA in 4 and previous coronary artery bypass graft CABG in 6 patients. Ten normalindividuals with no electrocardiographic, echocardiographic or stress test evidence ofischemiaserved as controls (6 males; 4 female, mean ages 49.4 +4.3 yr).Following clinical evaluation including 12 ECG and laboratory testing, sleep patternwas assessed using polysomnograph (PSG, Schwarzer) by putting the patient to sleep inthesleep lab for 12 hours concomitantly with 12 hours Holter monitoring of the cardiacrhythm.The blood pressure was monitored before and after sleep and during attacks of apnea.Parameters studied by the PSG included HR, O2 sat% and Apnea/Hypopnea index. Thelatterwas defined as; number of episodes of apnea or hypopnea per hour of sleep.