Background: Territorial health inequalities are of growing concern in countries with universal health systems. From 2003, three successive national cancer plans were launched in France, aiming to improve prevention and treatment. Regions in France are responsible for strategic and financial management of healthcare within their boundaries, which, until 2016, included up to 8 departments. In this study, we analyze the evolution of between and within-region territorial inequalities in breast cancer mortality over 50 years. Methods: We used direct and indirect standardization to analyze trends in breast cancer mortality for women aged 25 to 74 years between 1968 and 2017 in each department of metropolitan France. We analyzed the evolution of relative inequalities over time using standard errors of age-adjusted rates. We used multilevel Poisson regression to estimate how much the regional level contributed to territorial variation. Results: Over the period 1968 to 1992, breast cancer standardized mortality ratios (SMRs) increased (+16%) while relative territorial inequalities decreased (-21%). After 1997, SMRs decreased (-23%) but territorial inequalities remained unchanged. In 18 out of 22 regions, inequalities were lower at the end than at the start of the study period. Period proved to be the most important determinant of variation in mortality. However, multilevel models also suggested that the regional level explained most of the remaining variation in each period (from 50% to over 80%). Conclusions: Over the study period in most French regions, breast cancer mortality has decreased, and so have relative inequalities. Nevertheless, there is evidence that regions have performed differently. The proportion of variation explained by the regional level suggests the continued relevance of the health system on breast cancer mortality. Key messages:  Territorial inequality in breast cancer mortality has decreased in France over the 1968-2017 period. In most regions, disparities between departments have decreased.