Abstract INTRODUCTION: In Brazil, access to mammography is provided through the National Health System (SUS), the Supplemental Health System, or is paid for directly by the patient. SUS is the official government system and was established to conform to the constitutional requirement that health is a right of all Brazilian citizens and a duty of the state. In recent years SUS breast cancer control policies have advanced and government strategies for early detection have strengthened. However, evaluations are needed to monitor the effectiveness of these actions. OBJECTIVE: To describe the coverage of mammography in breast cancer screening conducted by the National Health System in Brazilian macro-regions and states in 2012. METHODS: An ecological study, where the estimate of coverage was the number of exams performed expressed as a percentage of the number of exams expected in the target population of women 50-69 years old. The exams performed refer to target population mammography production data from the Outpatient Information System (CIS) of DATASUS. To calculate the expected number of exams for this population, the biennial screening recommendations of the National Cancer Institute (NCI) and an estimate of the female population based on the census of the Brazilian Institute of Geography and Statistics (IBGE) were used. RESULTS: The coverage estimate for SUS-performed mammography in Brazil in 2012 was 26.6%. Stratified by macro region, the lowest coverage was in the northern region (12.1%) and highest in the South (34.6%). National coverage of screening mammography in Brazil, performed by the National Health System (SUS), according to the geographical regions.Macro-regionsCoverageMinimumMaximump*North Region12.10.227.2Northeast Region23.910.337.20.001Southeast Region28.515.532.5South Region34.630.341.0Midwest Region14.810.319.7* Chi-square test Units of the Federation an estimated coverage ranged from 0.2% to 41%, the lowest in the state of Amapa and the largest in Santa Catarina. 48% of states were in the range of 10.1% to 20% coverage. CONCLUSION: The results imply that the contribution of SUS to mammography screening in Brazil is higher in both macro-regions and states with higher income and better organised health system. Citation Format: Ruffo Freitas-Junior, Danielle CN Rodrigues, Rosangela S Correa, João-Emilio Peixoto, Rosemar MS Rahal. The contribution of the national health system to mammographic screening in Brazil [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-02-04.