Nuclear Magnetic Resonance (NMR) is a popular analysis technique in chemistry or biology but it is much less used in condensed matter physics and even less when the systems under investigation are ferromagnetic materials. However as a probe of the short-range chemical and topological order, NMR has proved useful to investigate the nanostructure of magnetic multilayers or granular systems and, in particular, to evaluate the nature, sharp or diffuse, of interfaces. In addition, NMR can probe selectively the magnetic properties of composite samples. Therefore NMR is a unique tool to investigate the correlation, at a local scale, between the nanostructure and the magnetic properties of a sample. For example, one can evidence the magnetic and structural in-homogeneities of the magnetic clusters and alloyed regions in nano-granular alloys. Some relevant results are presented, which have been obtained in the course of investigations of Co-based multilayers, ultrathin films and granular systems.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.