The influence of electric and magnetic fields on the possibility of disturbances of cardiac pacemakers and non-implantable insuline infusion pumps has been investigated at selected frequencies in the ELF-, VLF- and RF-range. Part 1 of the study covers laboratory investigation, in which the devices were embedded in a tissue-equivalent phantom and were exposed to well defined em-fields. The reactions of the devices have been recorded and evaluated. Part 2 contains the results of fieldstrength measurements performed at anti-theft-protection appliances and the mathematical evaluation of these results using national and international standards on electromagnetic compatibility. The results of the study show, that low-frequency electric and magnetic fields as well as pulsed rf-fields have the greatest ability of disturbing active electronic implants. An adverse effect of 50 Hz electric fields up to 10 kV/m did not appear in the subjects under test. The evaluation of the results of fieldstrength-measurements at anti-theft-protection appliances shows, that it is impossible to make a final conclusion on problems connected with these field sources. The risk depends on the parameters of the field (frequency, modulation, intensity) in a wide variety. An increased risk for carrier of pacemakers exists only in the vicinity of a of a few types of such appliances and during culmination of some adverse circumstances. The investigations on special problems will be continued.