OBJECTIVES: With the increasing demands for health care from aging society and rapid technological advancement, the National Health Security Office (NHSO) of Thailand demands for the development of systematic, transparent, and participatory processes for selection of new health interventions to be included into the benefit package of universal health coverage (UC) scheme.   This study reviews and describes experiences in the development of guidelines for economic evaluation and participatory process of key stakeholders in submission and topic selection of new health interventions into the UC benefit package.  Lessons learnt from this initiative are drawn in order to share experiences of Thailand to other developing countries. METHODS: Research methods comprise comprehensive literature reviews, focus group discussion, and brainstorming meeting among key stakeholders, working groups, and subcommittee members.  RESULTS: Research findings indicate that the draft guideline produced by several rounds of stakeholder consultations has been gradually accepted and adjusted by policy makers and key stakeholders.  Key features of the guideline comprise a) transparency in topic selection for economic appraisal with full engagement of key stakeholders; b) economic evaluation on selected interventions using incremental cost-effectiveness ratio (ICER); c) budget impact analysis. The ICER threshold of 1 GDP per capita for QALY gained has been applied by the Benefit Package Subcommittee of NHSO.  The six criteria for prioritization of topics were adopted in consensus by stakeholder consultations.  In Fiscal year 2010 and 2011, this guideline was successfully applied twice a year for topic selection, economic appraisal, and recommendations to the sub-committee and transmitted to NHSO Board for its final decision. CONCLUSIONS: This initiative not only produced and applied evidence informed decisions in a transparent manner; it also strengthened and sustained institutional capacities in generating evidence on ICER, budget impact assessment and other ethical social considerations. The NHSO subcommittee is the platform for interchange between evidence and policies.