Purpose: Previous studies have shown that those over 65 years of age had the highest rate of hospitalisations for diverticulitis compared to younger age groups. With an aging population and a disease with increasing prevalence with age, the outcomes of diverticulitis specific to older patients are overdue. This study aims to review the outcomes and recurrence rate in older patients. Methodology: This was a retrospective cohort study of all diverticulitis hospitalisations in adults between 2005-2020 in New South Wales, Australia. Admissions for diverticulitis were identified using ICD-10-AM codes from the Admitted Patient Data Collection (APDC). Older patients were defined as those aged 65 years and over. The primary outcomes were to review the trends in ICU admissions, readmissions, surgery and inpatient mortality in older patients. Secondary outcome was to assess the Hospital Frailty Risk Score (HFRS) in its ability to predict outcome in older patients. Results: There was a total of 38,325 older patients with a median age of 74 years. Complicated diverticulitis accounted for 14.3% of admission in this age group. Older patients were significantly more likely to require an ICU admission (OR 2.26, p<0.001) and have in-hospital mortality (OR11.9, p<0.001). However, they were less likely to have readmissions (OR0.78, p<0.001) and undergo surgery (OR0.75, p<0.001). The HFRS was strongly correlated with the need for ICU admission, surgery and in-hospital mortality. Conclusion: Older patients were less likely be admitted for complicated diverticulitis however the odds of ICU admission and in-hospital mortality were significantly higher. Assessment of frailty rather than age may be a more reflective measure of outcome.