The recent expansion of telecommunications, and in particular personal telecommunications, has led to a rapid increase in the number of radiotelephone (mobile, cellular phone) base station antennas erected. In order to address concerns about possible health effects related to the use of radiotelephones, the European Commission contracted an Expert Group to make recommendations for a programme of scientific research, the results of which could contribute to a health hazard assessment of the use of personal telecommunications. Whereas a large database exists for possible effects on human health from exposure to extremely low frequency (particularly power frequency) electromagnetic fields, there are far fewer data for radiofrequency (including mircrowave) fields, and very few related to the emissions and exposures specific to personal telecommunications. A comprehensive assessment of the risk of effects on human health requires such data. The research recommendations of the Expert Group are directed particularly towards collaborative research which is directly relevant to possible adverse effects on human health, and lends itself to attempted replication by other researchers in relation to the biological model, the biological endpoint examined and the exposure system and dosimetric techniques used. The Expert Group also provided recommendations on the management structure of a scientific programme; a mechanism for the participation of industry in financing it and in providing facilities and information; and an estimate of the magnitude of the financial resources required.