A large proportion of non-communicable disease can be attributed to modifiable risk factors such as poor nutrition and physical inactivity. We present data on planning and transport practitioners' perceptions and responses to government public health guidance aimed at modifying environmental factors to promote physical activity. This study was informed by questions on the role of evidence-based guidance, the views of professionals towards the guidance, the links between guidance and existing legislation and policy and the practicality of guidelines. A key informant 'snowball' sampling technique was used to recruit participants from the main professional planning organisations across England. Seventy-six people were interviewed in eight focus groups. We found that evidence-based public health guidance is a new voice in urban and town planning, although much of the advice is already reflected by the 'accepted wisdom' of these professions. Evidence-based health guidance could be a powerful driver affecting planning practice, but other legislated planning guidance may take priority for planning and transport professionals.