Background: Iran considers the revision of its health insurance benefit package (HIBP) as a means to achieve universal health coverage. Yet, its decision-making process has been criticised for being weak in terms of accountability and transparency. This paper reports on the development and implementation of the HIBP revision in Iran in the period 2019-2021, employing evidence informed deliberative processes (EDPs), a framework for benefit package design with the explicit aim of optimising the legitimacy of decision-making. Methods: The High Council for Health Insurance (HCHI) is coordinating the HIBP revision: it planned the six steps of the EDP framework with support from World Health Organisation and Radboudumc in 2019, and conducted a pilot project on multiple sclerosis diagnosis and treatment in 2020. Results: Implementation of the MS pilot project concerned the installation of advisory committees (involving some 60 stakeholders in supportive task forces, a technical working group and a national advisory committee), the selection of decision criteria (relating to quality of care, necessity, and sustainability), the inclusion of services for evaluation (nine in total), and the assessment and appraisal of these services. Conclusion: Implementation of the priority setting process for MS diagnosis and treatment services has likely improved the legitimacy of decision-making by involving stakeholders who engaged in deliberation based on available evidence in a stepwise, transparent process. It is expected to improve the quality of care for MS patients as well as its financial accessibility, at a zero net budget impact. The pilot project has served to help Iran’s health system move faster toward universal health coverage for a broader range of essential health services.