This study investigated the antitumour and chemosensitizing effects of celecoxib in the treatment of advanced colorectal cancer. A total of 90 patients were randomly divided into two groups: group CF was treated with a combination of celecoxib and the folinic acid-fluorouracil-oxaliplatin (FOLFOX4) regimen; and group F was treated with the FOLFOX4 regimen alone. Immunohisto chemical analysis of tumour tissues for cyclooxygenase-2 (COX-2) protein was performed. With regard to short-term efficacy, the response and disease control rates were significantly greater in group CF than group F. A log-rank test showed that the 3-year survival rate was significantly greater in group CF than group F. It was concluded that the addition of celecoxib to the FOLFOX4 regimen increased the short-term efficacy and the 3-year survival rate, and improved the quality of life of patients with advanced colorectal cancer. The antitumour and chemo sensitizing effects of celecoxib appeared to be independent of COX-2.