The proposed study would be the first randomized, double-blind, placebo (sham) controlled clinical trial to determine whether FMT delivered at colonoscopy is effective at preventing further relapse in patients who have suffered from at least a 3rd recurrence of CDI despite receiving standard treatment. The investigators hypothesize that FMT is superior to placebo in preventing relapse after treatment of CDI with vancomycin. As a result of this study, the investigators will have preliminary efficacy data for this novel treatment approach for recurrent CDI. The investigators will be better prepared to test the efficacy of FMT in future multicenter clinical trials. This research will advance clinical care, potentially impacting the protocol for treatment of relapsing C. difficile infection worldwide. This proposal includes collaboration with an investigator capable of performing microbiome analyses on specimens collected as part of the trial and will further understanding of the intestinal microflora in health and disease.