INTRODUCTION: The goal of Health Technology Assessment (HTA) agencies is to issue recommendations to inform decision makers about the incorporation of technologies. In general, the HTA process lacks transparency due to effectiveness and safety data dependent on ex post evaluation, the possibility of selective outcomes and bias in sampling, dosing and statistical analysis and economic evaluations based on unvalidated models and arbitrary threshold values. OBJECTIVES: The aim of this work is to evaluate methods to improve transparency on the HTA process. METHODS: Electronic search on Medline, Lilacs, Science Direct and Google Scholar and a complementary search in references of included studies and conference abstracts in January 2017. RESULTS: The transparency of the HTA process can be improved with the adoption of some concepts. The definition of a preferable health outcome can minimize uncertainty and make possible the evaluation of results of cost-effectiveness studies through a well established explicit threshold value, preferably defined by an opportunity cost approach. The use of risk sharing can be beneficial to public systems and suppliers provided that a good monitoring system is in place. Multicriteria Decision Analysis (MCDA) matrices can be useful to inform health professionals and society about the variables and weights considered in the analysis and facilitate the decision process. Public consultations previous to a recommendation are useful to include the general population’s preferences and social values into the HTA process. The adoption of the principles of value-based healthcare (VBH) tends to limit the price range of new interventions and facilitate negotiations between healthcare providers and suppliers. CONCLUSION: Adopting a well established preferable health outcome and the concepts of opportunity costs, VBH, risk sharing, MCDA and public participation, the HTA system tends to a situation where the decisions are made explicit and improved through rational methods adjusted by society’s preference.