The role of protein-RNA recognition is fundamental to many biological processes, protein-RNA interaction being at the heart of every molecular mechanisms controlling post-transcriptional gene expression. Deciphering the 3D structures of protein-RNA complexes is therefore of high significance. RNA binding proteins are very abundant in all kingdoms of life and often embed one to several small RNA binding domains. Since these domains often act as independent units, NMR spectroscopy is ideally suited to study the structure and dynamics of such domains in complex with their RNA targets. We review here how NMR spectroscopy has been used to solve the structure of more than fifty protein-RNA complexes and to understand for a few their dynamics.