This article reviews the variety of imaging modalities that are currently being used to evaluate the knee. Nuclear scintigraphy is discussed with emphasis on prosthesis abnormalities. Sonography is discussed with regard to the evaluation of popliteal masses. The uses of computed tomography, especially in the evaluation of the tibial plateau fracture, are discussed, and the role of fluoroscopy, computed tomography, and sonography in image-guided needle procedures are reviewed. Emphasis is placed on the role of MR imaging in knee imaging, with attention to internal derangements, bursal and capsular pathology, and other assorted intra- and extra-articular disorders. The focus of this article is to review the wealth of information that may be obtained by using these imaging modalities.