Observations from two patients receiving ipilimumab monotherapy and nivolumab plus ipilimumab provide evidence of the feasibility of faecal microbiota transplantation (FMT) for the resolution of immune-checkpoint inhibitor-induced colitis. Both patients had grade ≥2 colitis of a noninfectious aetiology. Stool samples were obtained from a single healthy donor with no gastrointestinal symptoms, sterile filtered, dissolved in a saline solution and applied directly to the caecum of each patient via colonoscopy. The first patient to receive FMT had complete resolution of colitis after a single dose, while the second patient had an initial partial improvement, albeit with ulceration and abdominal pain, which improved to complete resolution following a second FMT. 16s RNA sequencing data confirmed that bacteria initially present in the donor’s, but not the host’s, intestinal microbiota were incorporated into the host’s microbiota after transplantation. These findings warrant further investigation in a larger cohort of patients.