Osteoarthritis is a widely prevalent disease of the whole joint including cartilage, bone, and soft tissues. The increasing importance of imaging and assessment of all joint structures has been recognized. Conventional radiography is still the first and most commonly used imaging technique for evaluation of patients with a known or suspected diagnosis of OA, although its limitations are nowadays well known. MRI continues to play a critical role in understanding the natural history of the disease and in guiding future therapies, thanks to its ability to image the knee as a whole organ and to directly and three-dimensionally evaluate morphology and composition of articular structures such as cartilage and menisci. In this chapter, we will give insight into the roles and limitations of conventional radiography and MRI in the imaging of OA and describe the use of other modalities including ultrasound, tomosynthesis, computed tomography, and nuclear medicine in clinical practice and research in OA, particularly focusing on the assessment of knee. Lastly, we will describe the evolving application of artificial intelligence in the imaging of OA.