Abstract: ABSTRACT: OBJECTIVE To evaluate relationship between the K-ras gene mutation status and response to cetuximab/panitumumab for mCRC. METHODS By searching PubMed, CENTRAL, EMBSE, CNKI, ASCO and ESMO databases, the open published studies about the relationship between the K-ras gene mutation status and response to cetuximab/panitumumab for metastatic colorectal cancer were searched. The pooled ORR for metastatic colorectal cancer treated with cetuximab/panitumumab associated with the K-ras gene mutation status was calculated by statistic software Stata 11.0. RESULTS Twelve studies including 1 622 participants were include in this systematic review and Meta-analysis. The aggregated analysis showed the prevalence of K-ras mutation in mCRC was P=39%(95% CI: 37%-44%). The ORR (ORR=CR+PR) in K-ras wild type group and mutation group treated with aiti-EGFR were P=18%(95% CI: 15%-26%) and P=9%(95% CI: 2%-15%) respectively. The odds of ORR in K-ras wild type group was much higher than that in K-ras mutation group OR=5.10(95% CI: 2.84-9.14). CONCLUSION About 40% patients with mCRC have mutated K-ras gene which indicated the poor response to anti-EGFR treatment.