The aim of this study was to evaluate the objective tumor response rates and toxicities in elderly patients (older than 70 years) with advanced colorectal cancer treated with 5-fluorouracil (5-FU) as a first-line palliative chemotherapy regimen. Eighty-six consecutive patients were enrolled onto a retrospective study between January 1990 and February 1998. Patients were divided into two groups; group 1 consisted of patients who were 70 to 74 years old, and group 2 consisted of patients who were age 75 years and older. Four types of 5-FU-based chemotherapy were administered. First-line chemotherapy was continued until disease progression, unacceptable toxicity, or patient refusal. Primary tumor sites were the colon (n = 44), rectum (n = 29), and colorectal (n = 13). There was no difference in response (complete/partial) rates according to age groups (group 1: 21%, group 2: 26%). Median overall survival was 17 months for group 1 and 14 months for group 2, with 1-year survival at 63% and 55%, respectively (not statistically significant). Median time to progression was 6 months for both age groups. Chemotherapy in both groups increased performance status, and weight in 26% and 31%, respectively. No toxic death was reported. There was no difference in overall or severe toxicity between the two age groups, and all adverse events were manageable. Toxicity (grade III/IV) occurred in 25% of patients. Based on these findings, palliative first-line chemotherapy for colorectal cancer can be performed in selected elderly patients without increasing either morbidity or mortality, while obtaining response rates and side effects comparable to those in younger patients.