This paper presents  a discussion  of the issues, challenges and difficulties  of assessing the place of magnetic  resonance  imaging (MRI), a high cost diagnostic imaging modality, in the context of Australian health care, with reference to the study coordinated by the former National Health Technology  Advisory Panel (NHTAP).  This material follows from a presentation to an AIH workshop in health economics, held in 1988 and subsequent  developments in the NHTAP assessment.