The electromagnetic sources of interferences being able to deteriorate the operation of cardiac pacemakers or implantable defibrillators are numerous. This potential risk has been known since the release, 40 years ago, of pacemakers incorporating a detection circuit. Many papers, reviewed in this article, have been published about these conflicts. In daily practice, the risk of dangerous interference is weak, but it seems obvious that the implantable defibrillators are much more sensitive to the external environment than the cardiac pacemakers. With some precautions to eliminate manifest risk situation, it is possible to carry out a strictly normal life. Diagnostic memories increasingly sophisticated included in the new prostheses make possible the identification of asymptomatic conflicts, and the specification of the mechanism of a real problem. Provided information may also be useful to find solutions (adjustment, precautions) to decrease, even to remove the risks.