INTRODUCTION: In this paper we define and classify the health technologies in order to map its range of use in health care. Given the technology impacts on the performance of health systems, it is explored further, highlighting the importance of assessing it before selection, acquisition and use. Examples are presented from the developed countries where they have taken steps for the institutionalization of health technology assessment (HTA). We also assess the new developments in this regard. The Iranian health system is also assessed, emphasising the importance of HTA particularly in the context of health sector reforms.