The National Institute for Health and Care Excellence (NICE) is only one of several organisations internationally that uses economic evaluation as part of decision making regarding funding and pricing of new medical technologies. However, it can be argued that NICE has developed a more prominent international profile than most in their use of economics. After 20 years of operation, it is timely to assess the extent of NICE’s achievements, including the economic evaluation methods it has used and its willingness to adapt these as new evaluative approaches emerge and when NICE faces particular policy challenges. This paper considers some of the important policy and contextual developments in the UK over the last 20 years and how these may have shaped NICE’s approach to economic evaluation. It then assesses key areas of NICE methods, including perspective, defining benefits, modelling and uncertainty. The paper concludes that NICE has provided important support for the development of new methods, in particular through its role in identifying priorities for methods research funding and its sponsorship of the NICE Decision Support Unit. However, potentially important developments in methods in a number of important areas have yet to be formally included in NICE’s methods guidance and this should be addressed in the Institute’s 2019/2020 methods review.