Medical technology, defined broadly as the practical application of medical knowledge, is not always used effectively and efficiently because of imperfect prior assessment. Because of the scientific and financial implications of such inadequate technology assessment, many groups in the executive and congressional branches of the federal government, physician-sponsored organizations, nonphysician professional organizations, and organizations in the private sector have begun investigations of old and new technologies. After a description of these organizations and their activities, the problems of how to evaluate their impact and how to coordinate their work and avoid duplication and discussed. The needs for a neutral national oversight body, for broad societal input into decision making, and for a larger effort in technology assessment are emphasized.