Patients' associations are an example of biosocial groups, since their formation is motivated by common biological characteristics, such as rare diseases, and they are sometimes included in social movements in health. Even though the National Policy on Comprehensive Care for Persons with Rare Diseases was enacted in 2014, patients still struggle to ensure access to and treatment by the Unified Health System. The way in which associations of patients with rare diseases gain access to treatment via social networks, is investigated. This research is part of a study about the use of social media by associations of patients with rare diseases, which employs netnography - ethnography applied to the web - as the data-gathering method. Data sources were pages of the associations on Facebook in Brazil. It was seen that the activities of the associations are multi-faceted, ranging from patient and family guidance about treatment and quality of life, to active participation in the elaboration and implementation of public policies. The discourses suggest that the focus of patients' associations is, in the majority of cases, the access to drugs rather than the effective enactment of the national policy geared towards rare diseases.