Vascular ultrasound has an increasing role to play in the evaluation of numerous conditions such as peripheral vascular disease (PVD). Ultrasound imaging (b-mode and elastography) has been used for evaluation of vascular walls such as for deep venous thrombus (DVT) but there is also a need for flow assessment. With the increasing incidence of PVD, particularly related to diabetes, objective measures of flow in the extremities is important in medical management of such conditions. Doppler ultrasound can provide measurements of flow but generally in the major vessels and often relying on relative metrics such as pulsatility index, resistive index, etc. Subjective assessments are made in combination with selective limb compression or other conditions that would affect flow such as a Valsalva maneuver. Methods are being developed for more quantitative flow such as microvascular flow, ultrasound-based particle image velocimetry, Doppler vector flow, and contrast enhanced ultrasound (CEUS) as well as global flow metrics such as volumetric flow. This presentation will review some of the technology advances being made in the quantification of blood flow as these relate to vascular ultrasound.