Intermolecular and intramolecular interactions are crucial for almost all processes in chemistry, biology and biochemistry, and one of the most powerful techniques for monitoring these interactions is NMR spectroscopy. Many NMR experiments study biomolecules or small organic molecules under non-natural conditions, but these are still very similar to the native environments. In this chapter, our aim is to discuss NMR spectroscopy applications to drug design, enzyme inhibition, and the monitoring of host-guest interactions during the development of some novel drug formulations. In addition, other important protein-ligand and proteinprotein interactions will be discussed. Two NMR approaches are conducted for monitoring these interactions: one of these is based on the isotopic labeling of proteins and the other is based on the study of small molecules. Both techniques have a high impact on the examined cases. Finally, intermolecular and intramolecular interactions are used to study different metabolic pathways, and one very important NMR spectroscopy application includes metabolomics, where elucidation of characteristic chemical fingerprints for various biochemical processes can be achieved; this technique can be used to compare symptomatic, infected and healthy subjects.