Fecal microbiota transplantation (FMT) is the process of transplanting stool from a healthy donor into the gut of a diseased individual for therapeutic purposes. It has a clearly defined role in the treatment of recurrent (reclassified as " ") infection (CDI), with cure rates over 90% and decreased rates of subsequent recurrence compared with anti-CDI antibiotics. There is emerging evidence that FMT is also effective in the treatment of severe and fulminant CDI, with associated decreases in mortality and colectomy rates compared with standard antibiotic therapy. FMT shows promise as salvage therapy for critically-ill CDI patients refractory to maximum medical therapy and not deemed to be surgical candidates. FMT should be considered early in the course of severe CDI and should be delivered immediately in patients with signs of refractory CDI. Expansion of FMT's use along the spectrum of CDI severity has potential to decrease associated rates of mortality and colectomy.