Background: Faecal microbiota transplantation (FMT) has demonstrated variable efficacy in the treatment of active ulcerative colitis (UC) in three randomised control trials (RCT) to date. Interpretation of FMT RCT evidence is limited by each trial using a different donor stool processing method, placebo control, as well as timing and method of administration. Although the optimal approach is unclear, protocols involving a lower treatment burden may make FMT for UC more accessible. Methods: A multi-centre randomised, double-blind, placebo-controlled trial of FMT in adults with active UC (total Mayo 3–10 with an endoscopic Mayo sub-score ≥2) was performed. Anaerobically prepared donor stool (pooled from 3–4 donors) or autologous FMT (placebo) were stored frozen at −80°C, thawed and then administered via colonoscopy on day 0 followed by 2 enemas by day 7. The primary outcome was steroid-free remission of UC as defined by a total Mayo score of ≤2 with an endoscopic Mayo score of ≤1 at week 8. Secondary end points included clinical response (≥3 point reduction in Mayo score), clinical remission (Simple Clinical Colitis Activity Index ≤2), endoscopic remission (Mayo ≤1) and safety. A mandatory taper of oral corticosteroids was performed; those patients unable to cease oral corticosteroids were considered FMT non-responders. Results: 73 patients with UC were randomised; 38 received donor FMT and 35 received autologous FMT. 3 dropped out from the donor group and 1 from the autologous group during the 8 week observation period. In the intention to treat (ITT) analysis, 12/38 (32%) patients who received pooled donor FMT achieved the primary end point of steroid-free remission, as compared to 3/35 (9%) who received autologous FMT (p=0.02). In the per-protocol analysis, 12/35 (34%) vs 3/34 (9%) achieved the primary end point (p=0.02). In the ITT analysis, clinical response and clinical remission rates were 55% vs 20% (p<0.01) and 50% vs 17% (p<0.01) respectively. Steroid-free endoscopic remission occurred in 55% vs 17% (p<0.01). UC disease extent and disease duration were not significantly associated with achieving the primary endpoint in the donor FMT group. The frequency of serious adverse events (SAE) was not different between the donor and autologous FMT groups; 3 SAE's were recorded in the donor FMT group (1 worsening colitis, 1 Clostridium difficile colitis requiring colectomy, and 1 pneumonia) and 2 SAE's in the autologous FMT group (both worsening colitis). Conclusions: In active UC, one week of induction therapy with anaerobically prepared pooled donor FMT is more effective than placebo (autologous FMT) in inducing both clinical and endoscopic remission at 8 weeks.