This study is proposed to describe the supply and demand of Primary Health Care Service in thirteen municipalities of the southern half of Rio Grande do Sul State. For analysis, secondary data were obtained from the Data Processing Department of the Unified Health System (DATASUS). Data from appointments, procedures and structure of Primary Health Care Service were associated with concepts present in public policies and specific legal authorization. A quantitative study was carried out through the analyses of absolute frequencies of appointments and procedures from 2000 to 2005. Results showed diversified situations requiring primary health care service, which allowed different interpretations for the situations found. Among them, it can be cited the existence of a database with sub-notifications of appointments and procedures or even the absence of demand and/or supply for those within the municipalities researched. It is suggested the improvement of the mechanisms available for the analysis of primary health care services, which will enable the outlining of possible workflows, trajectories and therapeutic itineraries of users as well as the unveiling of likely local disparities regarding health.