The number of elderly breast cancer patients has been increasing recently nevertheless the optimal treatment for the elderly breast cancer patients still remains controversial. In this study, 21 primary breast cancer cases who were equal or older than 85 years old at our hospital were examined their clinical and pathological features. These 21 cases were divided into 2 group; Group A; ten cases who received operations, Group B; eleven cases who did not receive operations. T categories, M categories and clinical stages in Group B were significantly higher than those of Group A. The main causing reason why Group B cases had not received operations was that their primary breast cancer were too advanced to perform operation. Instead of operation, most Group B cases received endocrine therapy or radiotherapy. Group A cases received standard operative procedures including partial or total mastectomy and biopsies or dissection of axillary lymph nodes. Besides, their post- operative courses were good and safe. These results suggest that even for elderly patients, early diagnosis and treatment could improve their prognosis and quality of life. In addition, careful surveillances for elderly breast cancer patients, those who tend to stop attending regular check up to their hospital, should be considered for further assessment for characteristics of elderly breast cancer patients.