Magnetic resonance imaging (MRI) is a technique that utililises powerful magnets and radiofrequency to produce 3-dimentional images. MRI does not involve ionising radiation and has superb tissue resolution, enabling excellent delineation of anatomy as well as pathology in joints. This article briefly reviews the technical principle of magnetic resonance and discusses advantages and disadvantages of the technique, with particular attention to rheumatologic imaging. New information is summarised concerning the use of contrast media, dynamic, contrast-enhanced MRI, diffusion-weighted imaging, cartilage imaging and whole-body MRI.