This article outlines the benefits of imaging osteoarthritis with ultrasonography and some of the limitations. Pathologic structures able to be identified in osteoarthritis with ultrasonography are reviewed, with a focus on the validity of the technique. Common ultrasonographic abnormalities seen in osteoarthritis in specific joint regions are discussed. Finally, future research agendas are considered. With improving technology, accessibility of ultrasonography, increasing evidence regarding the validity, and use of ultrasonography in osteoarthritis mean that ultrasonography is likely increasingly used in the clinical trial setting and routine clinical practice to aid the diagnosis and management of osteoarthritis.