The first exploratory phase will take place in 34 subjects aged 18-60, with refractory established UC, over 12 weeks. Study type- It will be an open label 3 arm multicenter randomized controlled single blinded study, with review of endoscopic activity by blinded reviewers. Patients will be randomized to one of three groups; Group 1 will undergo standard fecal transplantation by colonoscopy on day 1 and 60 ml rectal enemas on days 2 and 14 from the same donor without dietary conditioning, while Group 2 will undergo the same transplantation (colonoscopy and enemas at night day 2 and day 14), with dietary pre-conditioning of the donor for 14 days and dietary treatment of the recipient immediately after transplantation and for the following 12 weeks.We will attempt to use the same donors for group 1 and 2 by using the preconditioning stool for group 1 and the post conditioning stool for group 2 in order to control for the "donor effect". Group 3 will receive dietary therapy only. Should the first stage be successful, The investigators will continue the fecal transplantation trial to reach our target enrolment number ( 76 patients) for transplantation. This second stage of the study will involve fecal transplantation in an additional 52 patients in order to have a total of 76 transplanted patients from the two phases.