Proteins are polypeptides of amino-acids involved in most of the biological processes. In the last 50 years, the study of their structures at the molecular level revolutioned the vision of biology. The three-dimensional structure of these molecules helps in the identification of their biological function. In this chapter, we focus our attention on methods for structure determination based on distance information obtained by Nuclear Magnetic Resonance (NMR) experiments. We give a few details about this experimental technique and we discuss the quality and the reliability of the information it is able to provide. The problem of finding protein structures from NMR information is known in the literature as the Molecular Distance Geometry Problem (MDGP). We review some of the historical and most used methods for solving MDGPs with NMR data. Finally, we give a brief overview of a new promising approach to the MDGP, that is based on a discrete formulation of the problem, and we discuss the perspectives this method could open in structural biology.