This chapter details the technical aspects of evaluation of the deep and superficial venous system. Here we detail the patient selection, equipment, and technical aspects of the exam. We also describe in detail the appropriate actions for a positive study. Where thrombus is clearly visualized within a vein, compression may be omitted to minimize the risk of embolization of thrombus. If thrombus is difficult to document due to the echolucent nature of the thrombus, gentle compression may be done to show abnormal response; however, utmost care should be exercised to apply only enough pressure to cause vein walls to come into gentle contact with the intraluminal thrombus. Pulsed Wave Doppler waveforms are to be obtained at the site of the thrombus to document absence of flow or diminished flow. Color Doppler may also be used to show absence of color filling in the affected area. Distal augmentation is to be omitted in the presence of visualized thrombus to minimize the risk of embolization.