In MSI-H colorectal cancers, we found a significantly higher intraepithelial infiltration with FOXP3-positive cells (median: 8.5 cells per 0.25 mm2vs 3.1 cells per 0.25 mm2 in microsatellite stable, P<0.001), and a significantly elevated ratio of intraepithelial to stromal infiltration (0.05 vs 0.01 in microsatellite stable, P<0.001). Here, FOXP3 is linked to colorectal cancer.