PURPOSE: Insulin-like growth factor binding protein (IGFBP-3) and phosphatase and tensin homolog (PTEN) are tumor-suppressor genes that may be involved in breast tumorigenesis. However, the roles of these genes in the regulation of breast cancer growth or progress are unclear. In this study, we aimed to find any correlation between the reduction of IGFBP-3 or PTEN protein expression in cancer tissues and the clinicopathological parameters in breast cancer. METHODS: We collected both cancer and adjacent normal tissues from 46 breast cancer patients (from January 1 to December 31, 2006), and checked the IGFBP-3 and PTEN protein levels in cancer and adjacent normal tissues using Western immunoblot. We evaluated the correlation of reduction status of IGFBP-3 and PTEN protein expression with variable clinicopathological parameters. RESULTS: The frequency of IGFBP-3 and PTEN protein reduction in cancer tissue, compared to adjacent normal tissue, was 63.0% and 34.8%, respectively. And in 87.5% of patients, who showed significant PTEN reduction, IGFBP-3 protein expression was reduced in cancer tissues. In contrast, IGFBP-3 protein reduced in only 50% of patients who didn't show PTEN reduction. However, we did not find any significant correlation between reduction of IGFBP-3 or PTEN expression in cancer tissue and variable clinicopathological parameters. CONCLUSION: The IGFBP-3 and PTEN genes were expressed in all breast cancer tissues. Nonetheless, we did not find any significant relationship between reduction of IGFBP-3 or PTEN expression and the clinicopathological parameters in this study. Therefore, further studies are needed to document the roles of IGFBP-3 and PTEN genes in breast cancer growth or progress.