The aim of this study was to understand the characteristics of older women with breast cancer and to describe the current patterns of treatment and outcomes. The study included data from the combined Auckland and Waikato breast cancer registers, which hold information for 12, 372 women diagnosed with stage I–IV breast cancer between June 2000 and May 2013. Of these women, 2671 (21.6%) were over 70 years of age. Patient characteristics, treatment type and survival were compared across four-year age groups (70–74, 75–79, 80–84, 85+) and hormone receptor status. Of the women aged over 70 years, 2485 (93.0%) had stage I–III disease. Increasing age was significantly associated with decreasing use of surgery, adjuvant radiotherapy, endocrine therapy and chemotherapy, even after adjustment for stage and level of co-morbidity. Nine hundred and one women (33.7%) had co-morbidities at the time of diagnosis. The 5-year breast cancer-specific survival rate for women aged 70–74 and that for women aged 75–79 were similar, but was worse in women aged over 80. Generally, older women are treated as per guidelines, although chemotherapy may be under-used. However, age is a significant factor influencing whether women are treated or not.