In a context where the efficiency and legitimacy of public action would seem to require a growing participation of citizens in collective decisions, our paper deals with the kind of deliberation that can be observed on electronic discussion forums provided by about thirty local French authorities on their websites. Indeed, the specific characteristics of forums (for example, asynchronic written exchanges, absence of face-to-face interaction, anonymity) lead us to reconsider the ways in which citizens may participate in the management of the city. The analysis of forums messages as well as interviews with the elected representatives and technicians have led to a more specific study of the rules, both formal and informal, which structure electronic exchanges, the arguments and skills used by net surfers in online discussions and the possible remodelling of cultural and social hierarchies which usually hinder citizens' expression.