The objective of the study is to investigate the efficacy of fresh, frozen or lyophilized fecal microbiota transplantation (FMT) via colonoscopy in patients with recurrent C. difficile associated diarrhea (RCDAD). We will generate a frozen, lyophilized or fresh fecal microbiota transplantation (FMT) inoculum from well-screened healthy volunteer donors of ≥150 gram/sample. Delivery of FMT will be performed colonoscopically. Fecal samples from donors and recipients will be saved for later metagenomic studies to characterize the microbiome of the gut in patients before and after FMT.