Combination chemotherapy of oxaliplatin, fluorouracil/leucovorin (FOLFOX) has reportedly become a standard regimen for colorectal cancer. In this study, we investigated the efficacies and adverse effects of modified FOLFOX6 (m-FOLFOX6) regimen in elderly patients. Thirty-nine patients with colorectal cancer, who received m-FOLFOX6 in our institution, were studied. Ten of the 39 patients, were older than 70 (elderly patients). Efficacies and adverse effects of m-FOLFOX6 were compared between patients over 70 years of age and those younger than 69 (younger patients). In terms of the response rate, there were no differences between the older and younger elderly patients. Moreover, the grade and frequency of adverse events were similar between them. We concluded that m-FOLFOX6 may bring about the same response rate in older and younger elderly patients. Moreover, m-FOLFOX6 may be given safely regardless of patient age.