To evaluate the toxicity and efficacy of a reduced dose intensity (mini-) FOLFOX-4 regimen as a first-line palliative chemotherapy in elderly patients (> or =70 yr of age) with advanced colorectal cancer, data from prospective databases at Seoul National University Bundang Hospital and Seoul Municipal Boramae Hospital were analyzed. A total of 20 patients were enrolled between January 2001 and August 2004, and were treated with oxaliplatin 65 mg/m2 on day 1, and with 2-hr infusions of leucovorin 150 mg/m2 followed by a 5-FU bolus (300 mg/m2) and 22-hr continuous infusions (450 mg/m2) for 2 consecutive days every 2 weeks until progression, unacceptable toxicity or patient refusal. Sixteen patients were evaluable for response with an overall response rate of 43.8%. Median progression-free survival was 4.8 months (95% CI: 3.0-6.7) and overall survival was 13.5 months (95% CI: 11.1-16.0). The main side effects were anemia and neutropenia, which were observed in 20.8% and 17.7%, respectively, of the total cycles administered. There were no grade 4 toxicities and only one patient suffered from febrile neutropenia. No grade 3 toxicities occurred except for anemia (5.2%) and vomiting (1.0%). In conclusion, the mini-FOLFOX-4 regimen was found to be well tolerated with acceptable toxicity, and to provide a benefit for elderly patients with colorectal cancer.