Manipulation of the enteric microbiota to restore normobiosis has therapeutic potential in IBD. Fecal microbiota transplantation (FMT), whereby fecal microbiota from a healthy donor is transplanted to a patient, is being studied as therapy for active UC patients. Currently three randomized controlled FMT trials have been published in patients with active ulcerative colitis with increasing success9-11. The investigators feel that the FMT success rate in active UC patients can be improved by solving the remaining pressing questions including the use of selected donors, preparation of the FMT, mode and frequency of administration. The investigators therefore designed a new multicenter interventional study with FMT to specifically answer these questions.