The article analyzes the implementation of the Family Health Strategy (FH) and discusses its potential to guide the organization of the Unified Health System in Brazil, based on the integration of FH to the health care network and intersectorial action, crucial aspects of a comprehensive primary health care. Four case studies were carried out in cities with high FH coverage (Aracaju, Belo Horizonte, Florianópolis e Vitória), using as sources: semi-structured interviews with managers and surveys with health care professionals and registered families. The integration analysis highlighted the position of FH Strategy in the health services network, the integration mechanisms and the availability of information for continuity of care. Intersectoriality was researched in relation to the fields of action, scope, sectors involved, presence of forums, and team initiatives. The results point to advances in the integration of FH to the health care network, strengthening basic services as services that are regularly sought and used as a preferential first contact services, although there are still problems in the access to specialized care. The intersectorial initiatives were broader when defined as integrated municipal government policy for the construction of interfaces and cooperation between the diverse sectors.