Natural electromagnetic elds (EMFs) and especially magnetic elds (MFs) have been factors that accompanied the development and evolution of the planet Earth and life on the planet.However, the role of natural and man-made MFs and EMFs in the origin and evolution of life and the effects of contemporary MFs/EMFs on human life are still not well investigated and understood. Both the hazard and benet of these elds are subjects of various studies and review papers, and very often the conclusion is that “this is a controversial issue.” I should partially agree with the statement, but the problem is not well dened. The general controversy is in the duration of exposure. The hazard from MFs/EMFs in natural and man-made conditions is due to continuous exposure to these physical factors. The most important issue here is that these elds act in long periods of time. Contrary, the benets in clinical use are results of short sessions of exposure to known MFs/EMFs in controlled conditions. It is now well understood that these therapeutic elds are orders of magnitude strongerthan natural elds.