About 4000 Danish employees may be significantly exposed to radiofrequency electromagnetic radiation (RF) or microwaves (MW) during work in the health sector or industrially. Exposure measurements and classifications are difficult, therefore, epidemiological as well as experimental research in the field is complicated. High exposure induces elevation of body temperature or local heating ("hot spots"). Some biological effects from RF/MW exposure seem to be mediated by heating, others are considered to be athermic. Epidemiological studies do not indicate that RF/MW should be carcinogenic, and experimental studies have not shown the radiation to be mutagenic or carcinogenic. Epidemiological studies among physiotherapists have indicated that RF may have reproductive effects. In one study, an association between ischaemic heart disease and exposure to RF is observed. The cataractogenic property of MW is supposed to be mediated by elevation in lens temperature following relatively high exposure. However, in the light of the problems in exposure classification, the epidemiological research may not be conclusive, and attempts should be made to improve the methods. In addition, Danish experience points out a number of methods of exposure reduction in the working environment.