AIMS Implementation of Health Impact Assessment (HIA) in Danish municipalities has been analyzed using the Roger's Diffusion of Innovation Theory. Municipalities were chosen from among those who presented their health policies on websites according to the status of inclusion of HIA into health policy. METHODS Qualitative interviews were conducted in 6 municipalities (3 with HIA inducted in their health policy and 3 without it) gathering information on knowledge and attitudes to HIA, barriers to its implementation, social system and communication channels used or expected to be used for implementation of HIA. RESULTS No significant differences were found among analyzed municipalities by status of HIA inclusion into health policy. Among barriers; a lack of tools with general validity, a lack of intersectoral working culture, balance between centralized versus participatory way of working and organizational structure of a municipality, and a lack of capacities were enlisted as most relevant. The last one is a crucial factor of an internal social system of a municipality. With regards to communication channels, reporting and presentation skills of implementers and doers are of key importance. CONCLUSIONS Systematic and sustainable capacity building is needed to achieve high level implementation of HIA in Danish municipalities. Development of validated tools, most importantly screening tools with focus on priorities of national public health policy would enhance implementation on municipal level.