In this article, Michel O'Neill, Ph. D., discusses the necessity of taking political factors into consideration when embarking on preventive programmes, regardless of the level in the community in which the intervention is to take place. When using the term, "political factors", the author is referring to the powers of influence which certain individuals or groups inevitably have over members of a community, regardless of its size. The influence is thus not necessarily linked to partisan politics but potentially has extensive implications for health promotion activities. After an introduction to the history of the development of a community health oriented system in Quebec, O'Neill presents four examples (at the local, regional, provincial, and federal levels) to introduce his analysis of political influence in community health and its implications in health promotion programmes. The marketing genius and tremendous budget of a multinational, American-based fast food corporation represents the political influence contrary of health promotion interests in two of the examples: competing with nutrition education efforts at a local level and "philanthropically" supporting curative efforts at a regional level. At a provincial level, the perpetual problem of tobacco corporations influencing elected officials in their social policies is presented while the aberration between rhetoric vis à vis policy and the reality of non-action is cited as political influence at a federal level. The examples cited are only four among "dozens and dozens" and serve as a reminder that health promotion professionals must take political influences into account if they wish to implement effective policies and programmes.(ABSTRACT TRUNCATED AT 250 WORDS)