This study aims to analyze the perception of managers of the Councils of Municipal Health Secretariats (COSEMS) and their contributions to the health regionalization process. We conducted thorough interviews with presidents of COSEMS of the states of Mato Grosso do Sul, Parana, Ceara, Tocantins and Minas Gerais. Data were analyzed with Iramuteq software, which generated a dendrogram with three themes: The first thematic axis: the prominent role of COSEMS in the regional governance process, which includes class 1 - COSEMS' leadership in the process of regionalization, and class 3 - The strategic experience of the regional agreement process. The second thematic axis includes the challenges to the provision of health care in the regions, consisting of class 2, which shows how to meet community needs, and class 4, which shows the local support carried out by COSEMS' teams. The third thematic axis consists of class 5, which describes the operational aspects of the provision of health care in the region. COSEMS play an important role in the regionalization process, especially because they have an organic performance and leadership. Its organic performance in these areas has ensured its legitimacy and leadership. It is a daily construction that ensures the advancement of collaborative governance in health regions.