Progress in medicine has often been initiated by discoveries and results from various disciplines of natural science. One of the most famous examples is the X-ray. In this case, its importance with respect to medical applications was immediately recognized and its development was propelled by fruitful cooperation between physicians and physicists. In other cases, e.g. that of NMR, the period between discovery and subsequent application in medicine was longer. Sometimes, a method has become established in clinical practice only after having passed through a long period of in vitro investigations and preclinical trials, while there are also applications that could only be seriously developed once crucial parts had been invented. Such cooperation between physicians, scientists, and engineers has proven effective and is certainly also a prerequisite for the continuing development of new methods or more sophisticated techniques and instruments. This is of particular concern for the application of magnetism in medicine. This second, completely updated and extended edition of the only reference work in this growing field of medical physics focuses on biomagnetic instrumentation as well as applications in cardiology and neurology. New chapters have been added on fetal magnetography and magnetic field therapy, as well as the safety aspects of magnetic fields. Following an introductory section, the well-known specialist authors from Germany, USA, Canada, Japan, the Netherlands and Scandinavia go on to cover biomagnetism, magnetic resonances, as well as magnetic substances and externally applied magnetic fields, before rounding the text off with a set of conclusions. The result is a manual for researchers in this field as well as for those who apply modern methods based on magnetism in medical practice. It equally provides a detailed overview for newcomers to the field as well as for experts familiar with only one part of the area.