The available imaging modalities in the evaluation and management of TAO are varied, each one having particular utility advantages and disadvantages (risks of contrast or delays in MRI and/or radiation in CT scan). Ultrasound (US) is an attractive assessment tool, a portable imaging device, and a reliable and reproducible method for the diagnosis, prognostication, and monitoring of inflammatory response. Orbital ultrasonography may quantify extraocular muscle enlargement and inflammation (topographic, quantitative, and kinetic echography), with the added benefits of ease, low cost, high accessibility, short exam time, and lack of radiation. The disadvantages of orbital US include poor visualization of the posterior orbit, inaccuracy in measurements, and user dependence. The purpose of this article is to explain the principles of the ultrasound techniques; explain the procedures, measurement, and interpretation of the results; evaluate the reliability and validity of this method for meaningfully measuring orbital inflammatory responses; and highlight the advantages and limitations of ultrasound in TAO.