Magnetic resonance imaging of the intensive care unit patient is a double edged sword. Whilst it offers unparalleled assessment of soft tissue structures, it requires careful preparation and special precautions. An awareness of the various cautions and contraindications to MRI is essential. The various different sequences permit the assessment of both the anatomy and function of various different organs. In the context of ICU, neurological indications for MRI are particularly important, both for diagnosis and prognostication.