AIM: To investigate whether krUppel-like factor 6 (KLF6) plays an important role in the development and/or progression of colorectal cancer. METHODS: A total of 123 formalin-fixed and paraffin-embedded colorectal cancer specimens were analyzed by immunohistochemistry using tissue microarray for the expression of KLF6 protein. The specimens were collected over a 3-year period in the laboratories at our large teaching hospital in Seoul, Republic of Korea. The correlation of KLF6 expression with clinicopathologic parameters was analyzed by x2 test and Bartholomew test. RESULTS: Normal colonic epithelium showed weak to moderate expression of KLF6, whereas reduced KLF 6 expression or loss of KLF6 expression was seen in 45 (36.6%) of the 123 colorectal carcinoma specimens. Interestingly, aberrant expression of KLF6 was detected in 25 (43.1%) of 58 cases with metastasis to regional lymph node and in 31 (47.0%) of 66 tumors more than 5 cm in size. Statistically, loss of KLF6 expression was significantly associated with tumor size (P<0.05). However, there was no significant correlation between KLF6 expression and Dukes’ stage (Bartholomew test, P>0.05), tumor location and lymph node metastasis (x2 test, P> 0.05). CONCLUSION: Loss of KLF6 expression may be a common and early event in colorectal carcinogenesis. AIM: To investigate whether krUppel-like factor 6 (KLF6) plays an important role in the development and / or progression of colorectal cancer. METHODS: A total of 123 formalin-fixed and paraffin-embedded colorectal cancer specimens were analyzed by immunohistochemistry using tissue The findings were collected over a 3-year period in the laboratories at our large teaching hospital in Seoul, Republic of Korea. The correlation of KLF6 expression with clinicopathologic parameters was analyzed by x2 test and Bartholomew test. RESULTS: Normal colonic epithelium was weak to moderate expression of KLF6, decreased reduced KLF6 expression or loss of KLF6 expression was seen in 45 (36.6%) of the 123 colorectal carcinoma specimens. Interestingly, aberrant expression of KLF6 was detected in 25 (43.1 %) of 58 cases with metastasis to regional lymph node and in 31 (47.0%) of 66 tumors more than 5 cm in size. Statistically, loss of KLF6 expression was sig However, there was no significant correlation between KLF6 expression and Dukes’ stage (Bartholomew test, P> 0.05), tumor location and lymph node metastasis (x2 test, P> 0.05). CONCLUSION : Loss of KLF6 expression may be a common and early event in colorectal carcinogenesis.