[영문]Objectives: This study assesses the impact of the English National Health Service (NHS) Health Technology Assessment (HTA) program using the “payback” framework.Methods: A survey of lead investigators of all research projects funded by the HTA program 1993?2003 supplemented by more detailed case studies of sixteen projects.Results: Of 204 eligible projects, replies were received from 133 or 65 percent. The mean number of peer-reviewed publications per project was 2.9. Seventy-three percent of projects claimed to have had had an impact on policy and 42 percent on behavior. Technology Assessment Reports for the National Institute for Health and Clinical Excellence (NICE) had fewer than average publications but greater impact on policy. Half of all projects went on to secure further funding. The case studies confirmed the survey findings and indicated factors associated with impact.Conclusions: The HTA program performed relatively well in terms of “payback.” Facilitating factors included the program's emphasis on topics that matter to the NHS, rigorous methods and the existence of “policy customers” such as NICE