Background We evaluated which patient factors were associated with treatment tolerance and outcome in elderly colon cancer patients. Design Population-based data from five regions included in the Netherlands Cancer Registry were used. Patients with resected stage III colon cancer aged ≥75 years diagnosed in 1997–2004 who received adjuvant chemotherapy ( N = 216) were included as well as a random sample ( N = 341) of patients who only underwent surgery. Results The most common motives for withholding adjuvant chemotherapy were a combination of high age, co-morbidity and poor performance status (PS, 43%) or refusal by the patient or family (17%). In 57% of patients receiving chemotherapy, adaptations were made in treatment regimens. Patients who received adjuvant chemotherapy developed more complications (52%) than those with surgery alone (41%). For the selection of patients who had survived the first year after surgery, receiving adjuvant chemotherapy resulted in better 5-year overall survival (52% versus 34%), even after adjustment for differences in age, co-morbidity and PS. Conclusion Despite high toxicity rates and adjustments in treatment regimens, elderly patients who received chemotherapy seemed to have a better survival. Prospective studies are needed for evaluating which patient characteristics predict the risks and benefits of adjuvant chemotherapy in elderly colon cancer patients.