Keywords: Health technology assessment, Rationale, Guideline development   Please follow the link below for full text. You may need to register (free-of-charge) as the article is published in Journal of the Medical Association of Thailand, Vol 91, No 6. http://www.jmatonline.com/index.php/jmat/issue/view/41/showToc   If you wish to read the second edition, please follow this link Guidelines