Magnetic resonance (MR) imaging of internal derangements and synovial chondromatosis is described. The MR findings of fluid collections, increased vascularity, partial disc displacement, and changes in disc morphology and length are among those factors that influence surgical execution. Fast imaging is particularly useful in delineating fluid and vascularity changes. Synovial chondromatosis is an entity characterized by large intra-articular fluid collections and is thus ideally evaluated using MR imaging.