Objectives: To investigate the effect of patient age on receipt of stage-appropriate adjuvant therapy for colorectal cancer in New South Wales, Australia. Materials and Methods: A linked population-based dataset was used to examine the records of 580 people with lymph node-positive colon cancer and 498 people with high-risk rectal cancer who underwent surgery following diagnosis in 2007/2008. Multilevel logistic regression models were used to determine whether age remained an independent predictor of adjuvant therapy utilisation after accounting for significant patient, surgeon and hospital characteristics. Results: Overall, 65-73% of eligible patients received chemotherapy and 42-53% received radiotherapy. Increasing age was strongly associated with decreasing likelihood of receiving chemotherapy for lymph node-positive colon cancer (p< 0.001) and radiotherapy for high-risk rectal cancer (p= 0.003), even after adjusting for confounders such as Charlson comorbidity score and ASA health status. People aged over 70. years for chemotherapy and over 75. years for radiotherapy were significantly less likely to receive treatment than those aged less than 65. Emergency resection, intensive care admission, and not having a current partner also independently predicted chemotherapy nonreceipt. Other predictors of radiotherapy nonreceipt included being female, not being discussed at multidisciplinary meeting, and lower T stage. Adjuvant therapy rates varied widely between hospitals where surgery was performed. Conclusion: There are continuing age disparities in adjuvant therapy utilisation in NSW that are not explained by patients' comorbidities or health status. Further exploration of these complex treatment decisions is needed. Variation by hospital and patient characteristics indicates opportunities to improve patient care and outcomes.