Mucosal-associated invariant T (MAIT) cells are an evolutionary conserved subset of innate-like T cells that are enriched in mucosal tissues within the human body.  Upon activation, MAIT cells rapidly produce cytokines that can regulate inflammatory responses in and around mucosal tissues. Mucosal cancers of the lung and large bowel are among the most commonly diagnosed human cancers in Australia and despite advances in conventional treatments, still maintain very high mortality rates. As mucosal cancers and pre-cancerous lesions involve a breach of the mucosal barrier, T cells within these areas may interact with resident microbiota. We are investigating MAIT cell activity in these tissues and whether it impacts cancer evolution and progression. Using flow cytometry and an array of microscopy techniques, we have analysed MAIT cells in human tissues containing both mucosal tissue and mucosal cancer. We are also investigating the function of MAIT cells within the tumour microenvironment, and whether there are changes in MR1 antigen presentation within this environment that influence MAIT cell responses.