The aim of the study was to compare the short- and long-term outcome of older and younger patients treated for colorectal cancer. We also wanted to study whether age was independently associated with post-operative mortality.We conducted a retrospective study of 503 consecutive patients treated for colorectal cancer. One hundred and six (21%) were 80 years of age or older. The median follow-up was 5.5 years (2-16.8 years) or until death.Post-operative mortality was 6% (0.7% in patients less than 65 years and 16% in patients over 80 years). Multiple logistic regression analysis showed that age, emergency operation, advanced T-stage, and ASA-class were each independently related to post-operative mortality. The overall estimated 5-year survival rate was 59% in patients less than 65 years and 24% in patients over 80 years. The cancer specific 5-year survival was 62% in patients less than 65 years and 45% in patients over 80 years.The study demonstrated that age was an independent risk factor for post-operative mortality. In very old patients surviving the post-operative period, the long-term outcome was good. Advanced age alone should not be used as a criterion to deny surgery for colorectal cancer.