Thoracic outlet syndrome (TOS) is caused by neurovascular bundle compression in the thoracic outlet space. Three pertinent structures may be compressed: brachial plexus, subclavian artery, and subclavian vein. Clinical presentation may be variable depending on the anatomical structure involved. We report a 36-year-old man with chronic recurrent pressure-quality left chest discomfort. Comprehensive cardiac investigations were nonrevealing. A venous and arterial duplex ultimately revealed dynamic venous and arterial compression. Our paper is to illustrate the sonographic approach to evaluate vascular compression in the thoracic outlet. We review the mechanisms of compression, and examination maneuvers to facilitate a Doppler-based diagnosis.