Owing to poor representation in trials, the optimum adjuvant regimen for elderly patients with stage III colon cancer is uncertain. We employed data from a cancer registry to show a survival benefit with the addition of oxaliplatin to fluoropyrimidine in patients ≥ 70 years. We note an increased rate of hospital admissions and early chemotherapy cessation in elderly patients on oxaliplatin. Background: Colon cancer is common in the elderly, but owing to under representation in clinical trials, the benefit of standard therapies is uncertain in this age group. We aimed to clarify the efficacy and complications of adjuvant oxaliplatin and fluoropyrimidine chemotherapy for patients 70 years and older with stage III colon cancer. Patients and Methods: All patients with stage III colon adenocarcinoma were identified from an Australian cancer registry (2006-2013). Multivariable Cox hazard regression was used to determine prognostic factors for all-cause mortality. Chemotherapy complications were quantified using discontinuation rates, hospital admissions, and mortality for 12 months after starting chemotherapy. Results: A total of 2164 patients fulfilled our inclusion criteria, including 1080 (49.9%) patients ≥ 70 years. Patients ≥ 70 years were less likely to receive adjuvant chemotherapy (60.7% vs. 89.6%) or oxaliplatin doublet chemotherapy (18.8% vs. 71.2%). Older patients receiving oxaliplatin were more likely to cease treatment early (18.7% vs. 7.6%) and require hospital admission (67.0% vs. 53.5%). The addition of oxaliplatin provided an overall survival benefit for patients < 70 years (hazard ratio, 0.44; 95% confidence interval, 0.3-0.6; P < .0001) and for patients ≥ 70 years (hazard ratio, 0.64; 95% confidence interval, 0.5-0.9; P = .005). Conclusions: Despite a modestly increased rate of hospital admission and early chemotherapy cessation, we demonstrate a persistent survival benefit for the addition of oxaliplatin to a fluoropyrimidine as adjuvant treatment for stage III colon cancer in elderly patients.