Injection rooms (or medicalised injected centres) allow people who consume psychotropic substances to access sterile and secure equipment. These welcoming spaces grant availability and caring for people living in extreme social vulnerability. Social work in these establishments is structured by relations of power which depends on the present actors and the situation. Using ethnographic tools, as the participative observation and the semi-structured interview, this work interrogates how relations of power structure works applications at the Abri d’Accueil. Using the concept of emotional work (from Arlie Russel Hochshild), it interrogates the sexed division of work and the different reactions from workers or consumers in sexist situations. Results show that female worker tends to carry more mental charges. Valuing participative production of knowledge, this work tends to defend transparency and horizontality with its methods: indeed, it reflects on a presentation of the results and the collaborative rereading, to avoid relations of power between an academic representant and the survey field.