PURPOSE: No clinically useful target molecule has been identified for triple-negative (TN) breast cancer, i.e., estrogen receptor-negative, progesterone receptor-negative, human epidermal growth factor receptor-2-negative phenotype, and its prognosis is poor. The aim of this study is to clarify the clinical and pathologic characteristics of triple negative breast cancer (TNBC). METHODS: The study subjects, 87 women with TNBC, were a subset of patients operated at Kosin University Gospel Hospital from January 2000 to December 2005. We examined pathologic characteristics such as tumor necrosis, infiltrating border, lymphocytic infiltration, prominent nucleoli in TNBC. And we studied the correlation between TNBC and several factors related to pathologic morphology. Chi-squared tests were used for statistical analysis. Kaplan-Meier estimates are presented for the survival function, and differences in survival were analyzed using the log rank test. RESULTS: Tumor necrosis was found in 51 patients (58.3%) in TNBC. And infiltrating border was found in 71 patients (81.0%). Also continuous lymphocytic distribution and prominent nucleoli was found in 31 patients (35.7%), 52 patients (59.7%), respectively. No association was detected between pathologic characteristics and other biological markers. Patients with tumor necrosis positive for TNBC didn't show shorter disease-free survival (P = 0.4490) or overall survival (P = 0.979) than patients without tumor necrosis. CONCLUSION: These findings suggest that pathologic characteristics cannot be used to classify triple-negative breast cancer into only two subtypes with differing prognoses. But because our study is small size study, more abundant patients' dates will be needed to evaluate the morphologic characteristics' predictive role.