Magnetic Resonance (MR) Imaging (MRI) is a state of the art imaging technology which allows cross sectional viewing of the body. The past 15 years have witnessed an explosion of information regarding the role of magnetic resonance imaging in assessing pathologic conditions of the ankle and foot. It does not use any ionizing radiation and has rapidly evolved into an accepted modality for medical imaging of disease processes in the musculoskeletal system, especially the foot. MR imaging is increasingly being recognized as the modality of choice for assessment of pathologic conditions of the ankle and foot. Magnetic resonance images provide a digital representation of tissue characteristics that can be obtained in any tissue plane. MRI is based on the principles of nuclear magnetic resonance (NMR), a spectroscopic technique used by scientists to obtain microscopic chemical and physical information about molecules. Magnetic resonance imaging has opened new horizons in the diagnosis and treatment of many musculoskeletal diseases of the ankle and foot. It demonstrates abnormalities in the bones and soft tissues before they become evident at other imaging modalities. The exquisite soft-tissue contrast resolution, noninvasive nature, and multiplanar capabilities of MR imaging make it especially valuable for the detection and assessment of a variety of soft-tissue disorders of the ligaments (e.g., sprain), tendons (tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, dislocation), and other soft-tissue structures (e.g., anterolateral impingement syndrome, sinus tarsi syndrome, compressive neuropathies [e.g., tarsal tunnel syndrome, Morton neuroma], synovial disorders). MR imaging has also been shown to be highly sensitive in the detection and staging of a number of musculoskeletal infections including cellulitis, soft-tissue abscesses, and osteomyelitis. In addition, MR imaging is excellent for the early detection and assessment of a number of osseous abnormalities such as bone contusions, stress and insufficiency fractures, osteochondral fractures, osteonecrosis, and transient bone marrow edema.