A briefsurvey ofthe application ofhigh-resolution proton andcarbon-13 n.m.r. spectroscopy for the investigation of the molecular conformations in proteins is presented. The first part of the paper recounts some basic relationships between structure and conformations of proteins and their n.m .r. spectral properties. These are then illustrated with recent experiments induding studies of thc basic pancreatic trypsin inhibitor, cytochrome b 5 and b 2 and isolated heme groups.