Background & aims. Clostridium difficile infection (CDI) is a leading cause of nosocomial diarrhoea in elderly people. This study aimed to describe the main clinical features and prognosis at 6 months of patients affected by CDI in a Geriatric Unit. Methods. Retrospective observational study based on clinical records conducted among elderly patients admitted to a Geriatric Care Unit. Inclusion criteria were: 1) patients discharged with diagnosis of CDI, confirmed by positive fast enzyme immunoassay for detection of C. Difficile toxin B on stool sample; 2) availability of Multidimensional Prognostic Index (MPI) score, assessed during the first 48 hours after admission. Secondary analysis was performed to investigate potential risk factors for worse outcomes during hospitalization, and on the incidence of recurrences and survival in a subgroup at 6 months of follow-up. Results. Thirty-three patients enrolled (23 F, 10 M), mean age 89 years. CDI was the reason for hospital admission in 39.6% of cases, while 60.4% developed the infection during hospitalization. All patients had undergone recent antibiotic treatment and 97% had recently been hospitalized or were nursing home residents. Ninety percent of subjects had more than two comorbidities and in 85% of cases, MPI predicted a high risk of mortality. In-hospital mortality was 21% and, in the subgroup of 16 patients who completed the 6-month follow-up, 31% had at least one recurrence and 75% died. Conclusions. CDI affects oldest-old and vary frail patients, with high comorbidity and high risk of mortality, and most of them have a poor prognosis, suggesting that CDI might be considered as a frailty marker itself.