This volume is based on a series of lectures delivered at a one-day teach ing symposium on functional and metabolic aspects of NMR measure ments held at the Middlesex Hospital Medical School on 1st September 1985 as a part of the European Nuclear Medicine Society Congress. Currently the major emphasis in medical NMR in vivo is on its poten tial to image and display abnormalities in conventional radiological im ages, providing increased contrast between normal and abnormal tissue, improved definition of vasculature, and possibly an increased potential for differential diagnosis. Although these areas are undeniably of major importance, it is probable that NMR will continue to complement con ventional measurement methods. The major potential benefits to be de rived from in vivo NMR measurements are likely to arise from its use as an instrument for functional and metabolic studies in both clinical re search and in the everyday management of patients. It is to this area that this volume is directed.