Qualitative research aimed to know and analyze the participation of health workers during the implementation of the MHC (Municipal Health Councils) of Campinas, 1990-94, to rescue the oral history of 6 key subjects, using semistructured interviews. Analysis revealed 3 themes: Background of Campinas MHC Constitution, the MHC Acting and Social representations of the UHS (Unified Health System), enabling understanding of the MHC creation and the role of workers and users to consolidate it.