Nuclear Magnetic Resonance (NMR) was first observed over 40 years ago and has recently also entered the field of human medicine. It currently attracts increasing attention from biologists and clinicians alike, and the scope of its different applications is in a phase of explosive development. Two principle developments of the MR method are taking place over the recent years and are of special interest for pediatricians and neonatologists. One involves the possibility of obtaining images from any part of the human body, somewhat similar to those obtained with computer tomography (CT), but without any radiation hazard. Today clinicians are most familiar with this mode of MR application. The other development tries to adapt the MR method of elucidating the structure of molecules used in physics, molecular biology and organic chemistry for applications in medicine, allowing to study metabolism in vivo under non-invasive conditions. Again, such studies pose no health hazards and are, therefore, applicable to neonates and small infants. They will enhance our understanding of metabolic processes during normal development and disease, especially in organs like the brain, where biopsies are virtually impossible. Recent developments combine the two methods mentioned above, in order to obtain morphological as well as metabolic information from the same organ at the same time, which may provide even better insight into pathophysiological mechanisms and their response to therapeutic measures. This article attempts to give an overview to the medical researcher, the clinician, and especially the pediatrician and neonatologist of what MR is and what we can expect from it.