Introduction: Fecal microbiota transplantation (FMT) has emerged as a safe and effective therapy for multiple recurrent and refractory Clostridium difficile infection (CDI). Previous studies have suggested a lower rate of success for FMT done in older patients; however, they were limited by inclusion of a small number of older patients. Given our experience with FMT in a relatively large number of older patients, our aim was to investigate the impact of patient age on the safety and efficacy of FMT. Methods: We conducted a retrospective cohort study of 234 patients with multiply recurrent or refractory CDI who underwent FMT at the Mayo Clinic in Arizona from 2011 to 2016. Medical records were reviewed and details regarding patient characteristics including medical comorbidities, CDI and FMT were obtained. FMT clinical response was identified by phone call at 1 week, 1 month, 3 month and 6 month following FMT. Patients were divided into groups based on age and comparisons of other patient-, CDI-, and FMT-related characteristics were compared. Results: Of the 234 patients who underwent FMT, 136 were >60 years old while 42 were >80 years old. When all patients were considered, 17 patients relapsed; six relapsed within the first week (early FMT failure), five more by 3 months and the remaining six at 6 months. Patients who relapsed were more likely to be older (75.3 versus 61.1, P=0.002) and male (64.7% versus 30.8%, P=0.002). This resulted primarily from a higher relapse rate among those >80 years old (47.1% versus 15.7%, P=0.001) (Table 1). Nevertheless, the overall success rate of FMT in those >80 years of age was 81.0% (34/42). Nearly all patients >80 years old underwent FMT via colonoscopy, similar to the younger groups. Among those patients >80 years old who relapsed, there were no significant differences in FMT-, CDI- or patientrelated characteristics compared to those <80 years old (Table 2). Finally, FMT was well tolerated in the elderly and there were no differences in adverse events across the age spectrum; there was, however, one major adverse event, a colonic perforation in an 88 year-old female.Table. CDI: Relapse by Age Category and Selected Other CharacteristicsTable: Table. Patient, CDI and FMT Characteristics of Relapsed Patients by Age ≥ or <80Conclusion: Age >80 years was associated with a higher likelihood of relapse after FMT for recurrent CDI, although the overall FMT success in this age group remained very good. Furthermore, FMT was safe and well tolerated and remains an important treatment modality for recurrent CDI in the elderly.