Background We determined to what extent patients with colon cancer stage III ≥ 75 years received adjuvant chemotherapy and the impact on overall and disease-specific survival. Patients and methods Data from The Netherlands Cancer Registry on all 8051 patients with colon cancer stage III ≥ 75 years diagnosed in 1997–2009 were included. Trends in adjuvant chemotherapy administration were analysed and multivariable overall and disease-specific survival analyses were performed. Results The proportion of stage III colon cancer patients ≥ 75 years who received adjuvant chemotherapy increased from 12%in 1997–2000 to 23% in 2007–2009 ( P < 0.0001), with a marked age gradient and large geographic variation. Five-year overall survival increased over time from 28% in 1997–2000 to 35% in 2004–2006 ( P < 0.0001). Sixty percent of patients died of colorectal cancer. Adjuvant chemotherapy was the strongest positive predictor of survival in this retrospective study (hazard ratio = 0.5; 95% confidence interval: 0.4–0.5). Conclusion There has been an increase in administration of adjuvant chemotherapy to elderly patients with stage III colon cancer in The Netherlands since 1997. Survival of elderly patients with stage III colon cancer increased over time, at least partly due to stage migration. The large effect of adjuvant chemotherapy on survival in this study is likely to be associated with the selection of fitter patients for adjuvant treatment.