The Korean Breast Cancer Society has constructed a nationwide breast cancer database through utilization of an online registration program. We have reported the basic facts about breast cancer in Korea in 2012, and analyzed the changing patterns in the clinical characteristics and management of breast cancer in Korea over the last 10 years. Data on patients newly diagnosed with breast cancer were collected for the year 2012 from 97 hospitals and clinics nationwide using a questionnaire survey, and from the online registry database. A total of 17,792 patients were newly diagnosed with breast cancer in 2012. The crude incidence rate of female breast cancer, including invasive cancer and in situ cancer, was 70.7 cases per 100,000 women. The median age at diagnosis was 51 years, and the proportion of postmenopausal women was higher than that of premenopausal women among those diagnosed with breast cancer. The proportion of cases of early breast cancer increased continuously, and breast-conserving surgery was performed in more cases than total mastectomy in that same year. The total number of breast reconstruction surgeries increased approximately 3-fold over last 10 years. The 5-year overall survival rate for all stages of breast cancer patients was extremely high. The clinical characteristics of breast cancer have changed in ways that resulted in high overall survival over the past 10 years in Korea, and the surgical management of the disease has changed accordingly. Analysis of nationwide registry data will contribute to a better understanding of the characteristics of breast cancer in Korea.