Peripheral arterial ultrasound is an important technique to evaluate vascular disease. Protocols include grayscale, color Doppler and spectral Doppler. Arterial duplex is used to evaluate patients with claudication to characterize atherosclerotic disease. Stenoses have characteristic findings which can help profile lesions accurately. Other nonatherosclerotic obstructive processes are also evaluable by duplex Doppler. Traumatic injuries can also be studied in the stable patient. Attention to protocols helps ensure optimal results.