Upper Airway Resistance Syndrome (UARS) is characterized with daytime sleepiness and cardiovascular disturbances, because of the repetitive increase of upper airway resistance leading to arousals. UARS, can easily be overlooked because the conventional polysonographic measurements are not sensitive enough to diagnose this syndrome, therefore the prevalence and morbidity of this syndrome is not known. Measuring the increased inspiratory effort by an esophageal balloon during the rising upper airway resistance is the gold standard technique for the diagnosis. Treatment of UARS is similar with Obstructive Sleep Apnea Syndrome (OSAS). In this article the clinical picture, diagnosis, and management of the UARS is reviewed.