As noted in the Foreword, this report is one of several volumes resulting from this study of future health care technology. The purpose of the study, as formulated by the STG, was to analyze future health care technology. Part of the task was to develop an 'early warning system' for health care technology. The primary goal of the project was to develop a list or description of a number of possible and probable future health care technologies, as well as information on their importance. Within the limits of time and money, this has been done. However, given the vast number of possible future health care technologies, complete information on the importance of each area could not be developed in any depth for all technology. Therefore, four specific technologies were chosen and were prospectively assessed. These future technologies were examined in more depth, looking particularly at their future health and policy implications. Subsequently, the project was extended to September 1987, and two additional technologies were chosen for assessment.