Metal ions play a crucial role in charge compensation, folding and stabilization of tertiary structures of large nucleic acids. In addition, they may be directly involved in the catalytic mechanism of ribozymes. Most metal ions applied in the context of nucleic acids in vivo and in vitro bind in a kinetically labile fashion. Hence, the detection of metal ion binding sites, not to mention the elucidation of the specific coordination sphere, still poses largely unresolved problems. Here we describe the different strategies applied and the progress made over the last years to characterize metal ion coordination to large nucleic acids by NMR.