The relation of EMF with cancer is two-sided: on one hand the International Agency for Research on Cancer has classified them as “possible carcinogens,” though we lack a strong experimental support for that, and, on the other hand, they can be used as a diagnostic and therapeutic tool for certain types of cancers. As often occurs, the situation is far more complex and multidimensional, since the effects of EMFs on biological systems depend on the physical parameters of the field and the type and physiological conditions of the biological system.