Background: This study aims to determinate the rate of thoracic outlet anomalies by means of analysis of cadavers.Methods: Supraclavicular incisions were applied by two anatomists and two thoracic surgeons in the thoracocervicoaxillary region of both extremities (n=40) in twenty cadavers (7 females, 13 males; mean age 46). The formation and type of fibrous bands, cervical ribs, C7 long transverse processes and anomalies of the clavicles, scalenus anterior and scalenus medius muscles, brachial plexus, subclavian arteries and veins were evaluated. The type and formation of fibrous bands were classified using Roos' classification.Results: Anomalies were found in 34 (85%) of extremities. The type 3-band was most frequently (15%) observed and all of them were on the right extremity. The type 4-band was rarely seen (2.5%). Two bands (type 9 and type 11) in the same extremity were notified in one cadaver. (2.5%). The occurrence rate of cervical rib and C7 long transverse process was 10%. Some fibers of m. scalenus medius emerged from a cervical rib in one extremity (2.5%). The arteria subclavia anterior passed through the scalene muscle in three extremities (7.5%). In 10% of extremities the C5 truncus passing through the anterior scalene muscle and upper truncus of brachial plexus passing anterior scalene muscle via perforation was found in 7.5% of patients.Conclusion: In our population, brachial plexus and subclavian artery variations are frequently observed. Therefore these types of anomalies should be taken into consideration to prevent morbidity and complications when muscle division or blockage applications are performed.