Background <p>Despite its potential with regard to the prevention and early detection of colorectal cancer (CRC), participation in the organized CRC screening programme of the Belgian region of Flanders is suboptimal. The role of language discordance as a determinant of screening participation in Europe is poorly understood, despite being identified as a potential barrier in qualitative and non-European studies.</p> Methods <p>In an ecological study analysing data on the level of Flemish municipalities (<i>n</i> = 300) from 2016 to 2021, we investigated whether the proportion of non-Dutch speakers at home is correlated with the response rate to CRC screening programme invitations and/or the total CRC screening coverage using multiple linear regression. We also performed Kruskal-Wallis tests and Dunn’s tests to examine municipal differences in screening based on their adjacency to the regions of Brussels and Wallonia.</p> Results <p>After adjusting for confounders, the proportion of secondary school pupils that primarily speak a language other than Dutch at home was associated with a lower screening response rate (β = -0.327, 95% CI -0.359; -0.296)) and lower total screening coverage (β = -0.195, 95% CI -0.219; -0.171). Response rates and coverage were higher in municipalities at least two municipalities away from the border with Wallonia, Brussels or France. Our findings suggest that a high proportion of French speakers is particularly indicative of linguistic barriers to screening in Flemish municipalities (β = -0.358, 95% CI -0.397; -0.319 for response rate and β = -0.213, 95% CI -0.238; -0.188 for total coverage).</p> Conclusion <p>Our study highlights the need to consider potential linguistic challenges when optimizing CRC screening policies.</p>