Telemedicine includes all medical activities in diagnosis, therapeutics or social medicine undertaken by means of an electronic transfer medium, thereby enabling the transmission of visual and acoustic information in these fields over long distances without the doctor being personally present at the requested consultation. Most experience in telemedicine has been gathered in diagnosis, especially with respect to teleradiology and telepathology; however, an increasing number of institutions have obtained experience in teledermatology, telepsychiatry, telecardiology, telesurgery, etc. The quality of the transmitted images is adequate for diagnostic application. However, the transfer rates of normal telephone lines are not satisfactory and these telephone nets will be replaced by ISDN and broad band or satellite connections in the near future. The lack of uniform transfer standards is the most important constraint in telepathology. This fact is one explanation for the fast growth of the Internet, which is based on unified transmission standards. The rapid expansion of telemedicine is inevitable and the increased use of this tool will induce profound changes in the medico-social environment. There is a fear of institutional concentration, at the expense of small institutions. This development can be minimised by augmenting the scope to encompass telemedicine in all interdisciplinary fields, with the consequent full integration of small institutions. Telemedicine is an appropriate technique for quality assurance in all areas of medicine, since it permits simultaneous "soft" quality control, in conjunction with assumption of co-responsibility by the control institution.