This article aims to illustrate and critically analyze the results from the 1-year experience of using health technology assessment (HTA) in the development of the Thai Universal Coverage health benefit package. We review the relevant documents and give a descriptive analysis of outcomes resulting from the development process in 2009-2010. Out of 30 topics nominated by stakeholders for prioritization, 12 were selected for further assessment. A total of five new interventions were recommended for inclusion in the benefit package based on value for money, budget impact, feasibility and equity reasons. Different stakeholders have diverse interests and capabilities to participate in the process. In conclusion, HTA is helpful for informing coverage decisions for health benefit packages because it enhances the legitimacy of policy decisions by increasing the transparency, inclusiveness and accountability of the process. There is room for improvement of the current use of HTA, including providing technical support for patient representatives and civic groups, better communication between health professionals, and focusing more on health promotion and disease prevention.