Background/Aims: Cetuximab is currently approved for the treatment of metastatic colorectal cancer (mCR) with KRAS wild-type. Prior few studies demonstrated that G13D mutated tumors could benefit from cetuximab. This study aims to investigate whether KRAS G13D mutated tumors benefit from cetuximab in the chemotherapy refractory patients. Methodology: We retrospectively compared progression-free survival (PFS), overall survival (OS) and response rate (RR) according to KRAS mutation status in 105 patients with mRC treated at the Cerrahpasa Medical School Hospital, between October 2008 and October 2011, with cetuximab alone or in combination with chemotherapy. Results: PFS was significantly longer in patients G13D mutated tumors (6.81 months) than in patients with other KRAS mutated tumors (5 months) (p=0.027). No significant difference in PFS. between patients G13D mutated and KRAS wild-type tumors was detected. No significant difference in OS was detected in patients between G13D mutated tumors and other KRAS mutated tumors. However, patients with KRAS wild-type tumors had significantly longer OS (16.1 months) than patients with mutated tumors (8.9 months) (p=0.025). RR in patients with other KRAS mutated tumors, was significantly worse than those with G13D mutated tumors (p=0.002). Conclusion: Our study demonstrated an association between the presence KRAS G13D mutanted and survival chemotherapy in refractory metastatic colorectal cancer treated with cetuximab.