Faecal microbiota transplantation (FMT) is effective at treating recurrent Clostridioides difficile infection (rCDI) and is now recommended within clinical guidelines. Although success rates are consistently high for rCDI (>90%), efficacy in treatment of ulcerative colitis (UC), one of the main subtypes of inflammatory bowel diseases, have been less impressive. In those with mild to moderate UC, FMT induces remission in 30-40% of patients, emphasising the need to identify microbial and host markers that are associated with treatment success. I will present our work assessing the utility of FMT in the treatment of UC and understanding what properties make FMT successful in these patients. This includes discussion of our donor selection strategies, randomised clinical trials of FMT in UC, studies on microbial markers of therapeutic response in patients as well as donor efficacy, and more recently, studies on host markers of disease remission. Our findings may be of importance in optimising donor selection and designing future live microbial therapeutics for UC, and in the discovery of potential druggable targets in UC.