In this study, we analyzed Claudin-1 and Claudin-4 expressions in colon carcinomas. We investigated the relationship between the expression of these tight junction proteins and clinicopathologic parameters. Claudin-1 and 4 expressions were determined by immunohistochemical methods, and the rate of cells expressing these tight junction proteins were calculated with stereologic methods. Fifty-nine colon cancer cases were enrolled in the study group. Claudin-1 and 4 expressions were found to be significantly lower in cases with lymph node metastasis. Mean staining rates of Claudin-1 and 4 in lymph node (+) cases were 36.1 +/- 20.1 and 58 +/- 28.9, while in lymph node (-) cases, these were 63.8 +/- 25.9 and 72.3 +/- 25.6, respectively (p = 0.0005 for Claudin-1, p = 0.049 for Claudin-4). The mean staining rate for Claudin-1 in adenomatous polyps was significantly higher than incarcinomas (77.13 +/- 23.4 and 50.6 +/- 26.93, respectively) (p = 0.003), while it was quite similar for Claudin-4 (65.4 +/- 26.9 and 65.3 +/- 27.9, respectively).