There is considerable interest in measuring the performance of health systems world-wide. In developed countries, primary concerns about health system performance include costs, equity in access, quality of care and patient safety, and how to tackle the long-term implications for health systems of ageing populations together with prevention and management of chronic diseases. In the developing world, it is increasingly recognized that health systems constraints in terms of financial resources and human resources for health have restricted progress towards the MDGs.\n\nThis short paper describes the objectives of health system performance assessment (HSPA) in Thailand and the general framework for assessing health system performance of the country. Available and missing data for assessing health system performance using WHO framework on six building blocks are also explored and mapped. It is found that governance and responsiveness are two missing areas of HSPA that need to be further developed in HIS in Thailand. Lessons from HSPA in Thailand indicate that key contributing factors include demand for HIS from policymakers and changes in their behaviors to use evidence for decision making. Adequate financing, networking, and skillful human resources and long term capacity building with good collaboration between data producers and data users are also key contributing factors. The remaining key challenges in institutionalizing HIS in Thailand include difficulties in networking, and standardization of data generation, collection, and data analyses among many HIS institutions. Gaps in data quality and availability, particularly the private sector, and long term capacity building in each component of HSPA are other challenges that need to be addressed