Abstract: Objective：To evaluate the clinical efficacy and safety of cetuximab plus irinotecan in the treatment of metastatic colorectal cancer, and to investigate the correlation of KRAS mutation and clinical efficacy. Methods ：Analyzed the 15 patients of metastatic colorectal cancer with histologically confirmed diagnosis treated with cetuximab in combination with irinotecan or FOLFIRI regimen．KRAS mutation was detected in 12 tumor tissues and investigated the correlation of KRAS mutation and clinical efficacy. Results：(1)Efficacy analysis: The Objective： response rate was 26.7％, 4 patients with PR(partial response), 7 patients with SD(stable disease) and 4 patients with PD(progression disease). The disease control rate was 73.3％ and the median time of tumor progression was 16 weeks. The major toxicities were acneform eruptions, diarrhea and bone marrow depression,their incidence rate was 80％(12/15).46.7％(7/15) and 60％(9/15) respectively. In 12 acneform eruptions patients, the Objective： response rate was 33.3％ and the disease control rate was 83.3％. (2)Correlation of KRAS mutation and efficacy: KRAS gene was detected in 12 patients. 7 patients of KRAS were wild type, and the Objective： response rate was 28.6％, the disease control rate was 85.7％ and the median time of tumor progression was 18 weeks. 5 patients of KRAS were mutation type, and the Objective： response rate was 20％, the disease control rate was 60％ and the median time of tumor progression was 12 weeks. Because of less cases, the difference had no statistical significance. Conclusion：Cetuximab in combination with irinotecan has clinically significant activity in patients with refractory metastatic colorectal cancer．The toxicity，except rash ，is not more frequent among the patients receiving cetuximab in comb ination with irionotecan than irionotecan alone．Acneform eruptions maybe prognosticate clinical benefit. Therapeutic effect of the patients with wild type KRAS may superior to those patients with mutant type KRAS when receiving cetuximab therapy.