Thoracic outlet is a tight anatomic space crowding of important neurovascularcomponents that traverse the space. Thoracic outlet syndrome consists of symptomsthat affect the neck, shoulder & upper extremity caused by compression or irritationof the brachial plexus, subclavian vein & subclavian artery as these structures passthrough the thoracic outlet& the costoclavicular space. A variety of terms have beenused to describe this syndrome, first rib syndrome, costoclavicular syndrome,shoulder-hand syndrome& scalenus anterior syndrome. The syndrome developsbecause of abnormalities of the first rib, the scalenus anterior muscle, the clavicle ora cervical rib. Pain and paresthesia are commonly present. Arterial compression ismuch less common. Edema and venous distention occur with venous compression.Hanauld who published an article in 1742, is credited by keen as being the first todescribe the importance of the cervical rib. The treatment of thoracic outletsyndrome is either conservative or surgical .The conservative program should bepersuaded for as long as it seems effective, as long as the patient can toleratesyndrome. Also scalenotomy and combined approach are used. Complications ofoperations of TOS decompression may be very serious such as vascular injury andnerve injury, which should be managed properly.