BACKGROUND: Dairy consumption has been associated with various health outcomes that may be mediated by changes in gut microbiota. METHODS: This cross-sectional study investigated the association between the colonic mucosa-associated gut microbiota and the self-reported intake of total dairy, milk, cheese, and yogurt. A total of 97 colonic mucosal biopsies collected from 34 polyp-free individuals were analyzed. Dairy consumption in the past year was assessed using a food frequency questionnaire. The 16S rRNA gene V4 region was amplified and sequenced. Operational taxonomic unit (OTU) classification was performed using the UPARSE and SILVA databases. OTU diversity and relative abundance were compared between lower vs. higher dairy consumption groups. Multivariable negative binomial regression models for panel data were used to estimate the incidence rate ratio and 95% confidence interval for bacterial counts and dairy consumption. False discovery rate-adjusted RESULTS: Higher total dairy and milk consumption and lower cheese consumption were associated with higher alpha microbial diversity (adjusted CONCLUSIONS: Dairy consumption may influence host health by modulating the structure and composition of the colonic adherent gut microbiota.