The public health risk communication in social media provides a new communicative expression of Brazil´s Health Surveillance services (HSS). The general objective of this research is to reveal possibilities, strengths and frailties of this communication, in order to gather information to help the analysis: does it reinforce the right to health? Facebook pages of HSS were identified and their posts related to health risks were analyzed. We assume that those pages represent Mediatized Worlds which interpretation enables to reflect about what it has been communicated and how. The actual study consists in a qualitative, exploratory research. In order to present a general map of HSS pages on Facebook, Netvizz was used as web tool to data mining. Additionally, posts published between 06/01/2017 and 12/01/2017, by Anvisa Oficial and Vigilância Sanitária Rio fanpages, were collected. Despite the public nature of posts, with respect of ethical criteria, both Anvisa (Federal Health Surveillance agency) and Rio de Janeiro´s Health Surveillance service were consulted about their permission to join the study. The analytical phase has utilized a combination of techniques. Social Network Analysis was used in order to organize collected data according to Key Performance Indicators and metrics related to posts from a selected period. Content Analysis from Laurence Bardin was used to reveal the posts' themes. Those themes were identified for the 30 posts associated with higher engagement: medicine was the theme of highest posts engagement on Anvisa Oficial fanpage and zoonoses control was the most engaged theme for Vigilância Sanitária Rio fanpage. Transversality and the central role of communication are the basis of discussion. Final considerations were generated from reflections about the results and its inferences towards to risk communication contents and the way they relate to political, economy, culture, health law, social science, public and collective health fields. Regardless of many failures in the communication process, such as insufficient dialogs and participation, Health Surveillance pages succeeds in problematizing importante issues of sanitary practice through their communication on Facebook. That helps us to believe it is an essential factor to consolidate the right to information and the right to health by democratic means.