Developing imaging technologies capable of identifying unstable atheromatous plaques in vivo is a major issue of clinical cardiovascular research. These techniques would permit an earlier surgical or medical therapy and would anticipate acute ischemic syndromes. Plaque vulnerability depends on the relative amount and thickness of its lipid core and fibrous cap. Several means of assessing atherosclerotic plaque composition have been used with nuclear magnetic resonance (NMR): carbon-13 and proton spectroscopy, proton imaging, chemical shift imaging, water diffusion imaging, and magnetization transfer. Recent data have shown that MR allows for accurate in vivo diagnosis and may support large scale prevention studies.