Since 2004, the Subcommittee for Development of the National List of Essential Drugs (NLED) has embarked upon an historical evolution of applying evidence to the revision, inclusion and exclusion of medicines into and from the list. Then, the revision of the 2008 NLED was the first time in Thai history where the drug selection process in Thailand formally incorporated pharmacoeconomics. At present, the lack of a standard methodology for conducting economic evaluation is a major barrier that diminishes the potential use of economic evidence. The development of national economic evaluation guidelines by a group of national experts was subsequently endorsed by members in the Subcommittee as useful tools for future NLED revision. They emphasize that these guidelines should be applied not only to those evaluations conducted by public institutions but also by private pharmaceutical companies that often use this evidence for their marketing, or even for future requirements of economic information from industry, as complementary evidence for inclusion of health technology.