Physiologic assessment of lower limb peripheral artery occlusive disease is based on indirect physiologic measurement of ankle-brachial systolic pressure index (ABI) and recording ultrasound tibial artery waveforms. Duplex ultrasound testing affords direct tibial artery imaging and assessment of pulsed-Doppler tibial artery waveforms, which is more accurate then measurement of ABI for peripheral artery occlusive disease severity assessment. Tibial artery peak systolic velocity (PSV) is of particular value in the evaluation of patients with incompressible tibial arteries producing a falsely elevated ABI. Calculation of the ankle-profunda index (average tibial artery PSV/proximal profunda femoris artery PSV) also correlates with ABI reduction and can be used as an additional measure of peripheral artery occlusive disease. Tibial artery PSVs can be used to supplement ABI as an objective outcome measure after peripheral arterial interventions, and this aspect of duplex scanning warrants further clinical research.