.Carotid duplex ultrasound (CDU) is non-invasive and reliable method for assessment of carotid artery disease and it provides crucial information for the decision of carotid endarterectomy or stenting. However, various artifacts occur during CDU and, therefore, understanding artifacts is substantial for appropriate CDU examination. Artifacts encountered during duplex ultrasound examination are assigned into artifacts in B-mode ultrasound and Doppler artifacts. Artifacts in B-mode ultrasound can occur in any step during the course of ultrasound progress such as propagation-path, resolution or attenuation. Doppler artifacts are originated from inappropriate setting or are related with anatomical problem. For obtaining more information from carotid duplex ultrasound, not only substantial knowledge about artifact itself but also knowledge about physics and training for improving scanning skill are needed. Journal of Neurosonology 1(1):1-9, 2009

Key Words: Ultrasound, Artifact, Carotid arteries, Doppler