Klotho is one of the known anti-aging genes, and functions as an inhibitor of the insulin-like growth factor 1(IGF-1) pathway. However, the clinical significance of Klotho expression in cancer tissues have not been elucidated yet. In this study, we aimed to investigate the clinical significance of Klotho expression in breast cancer patients. We evaluated Klotho expression through immunohistochemical analysis and evaluating Ki-67 positive cell index in 142 patients who underwent surgery for breast cancer in our hospital. There was no significant correlation between age, menopausal state, historical type, hormone status, HER2 status, and distant metastases. High expression of Klotho was observed in the non-invasive compared to the invasive ductal carcinomas. The number of metastatic lymph nodes, clinical stage, and tumor size were correlated to Klotho expression level in the cancer tissues. The Klotho positive group exhibited low score for Ki-67 positive cell index than the Klotho negative group. No significant correlation in cumulative survival rates between Klotho positive and Klotho negative groups was observed. The Klotho negative group exhibited good prognosis than the Klotho positive group for the disease- free survival after the operation. These results suggest that the analysis Klotho expression in the breast cancer tissues using immunohistochemistry is a useful tool to assess the disease-free survival for breast cancer patients.