Color duplex sonography of the thoracic inlet veins produces a spectrum of normal and abnormal findings. These vessels include the internal jugular, innominate, subclavian, and axillary veins. Although venography is the traditional means of imaging these veins, ultrasound lends itself to assessment of these vessels by providing anatomic and hemodynamic information. Advances in gray-scale resolution and color Doppler technology permit direct visualization of thrombus, stenosis, collateral vessels, catheters, and stents, as well as sensitive spectral waveform analysis. Abnormal findings in the thoracic inlet veins include locally elevated velocities at stenoses with low velocities peripherally. Thrombus, extrinsic compression, and collateral vessels may also produce abnormal findings. Common interpretive pitfalls are caused by transducer pressure, deep inspiration, slow flow, collateral veins, large-bore catheters, and hemodialysis fistulas. A thorough knowledge of the regional anatomy, normal and abnormal waveforms, and commonly encountered pitfalls will optimize the accuracy of color duplex sonography of the thoracic inlet veins.