OBJECTIVES: The EGFR plays an important role in tumorigenesis and tumor progression of colorectal cancer, and leads to the activation of intracellular signaling pathways. The use of anti-EGFR-targeted therapy has increased for patients with colorectal cancer, but patients with EGFR mutations will be resistant to anti-EGFR-targeted therapy. The identification of gene mutations is critical in cancer treatment; therefore, the aim of this study is to investigate the incidences of EGFR mutations in colorectal cancer patients in Korea. METHODS: We reviewed 58 colorectal cancer patients who underwent operations between 2003 and 2006, retrospectively. We analyzed their EGFR mutations in 4 loci by DNA sequencing. In addition, we analyzed the correlation between the presence of EGFR mutation and patients' clinicopathologic features. RESULTS: Of the 58 patients, 35 patients were male and 23 were female. Their mean age was 63.28+/-11.18 years. Two patients (3.45%) were diagnosed as stage Tis, 7 patients (12.07%) had stage I, 24 patients (41.38%) had stage II, 20 patients (34.48%) had stage III, and 5 patients (8.62%) had stage IV. As a result of mutational analysis, EGFR mutations on exon 20 were detected in 13 patients (22.41%, G-->A transitions). EGFR mutations on exon 18, 19 and 21 were not detected. EGFR mutation increased in the earlier stage and the absence of lymph node metastasis (P=0.028). CONCLUSION: The incidence of EGFR mutation in Korean colorectal cancer patients is 22.41%. In addition, EGFR mutation significantly increased in the earlier stage and the absence of lymph node metastasis.