OBJECTIVES: To describe real-world treatment patterns and key clinical outcomes among postmenopausal patients with estrogen receptor–positive (ER+)/human epidermal growth factor receptor 2–negative (HER2−) metastatic breast cancer (MBC) in the United Kingdom, Canada, Belgium, and the Netherlands. METHODS: This was a retrospective study of medical record data from postmenopausal patients treated for ER+/HER2− MBC in four countries. Eligible patients discontinued second-line treatment of metastatic disease between January 1, 2008, and March 1, 2014. Data from all countries were combined to assess patient characteristics, treatment patterns, time to progression (TTP), and progression-free survival. RESULTS: Information was provided on 438 patients by 107 medical/clinical oncologists. Patients’ mean age was 61.6 years at metastatic diagnosis, and 85.2% were white. The majority of MBC patients had de novo metastatic diagnosis (62.3%); 37.7% progressed from earlier stages. The most common sites of metastasis were bone (66.4%), lung/pleura (47.0%), liver (37.9%), and lymph nodes (34.9%); 69.9% had visceral disease. In the first-line MBC setting, 56.6% of patients received endocrine therapy (ET) alone, 26.0% received chemotherapy (CT) alone, and the remainder received both (in combination [6.4%] or CT followed by ET [11.0%]). During second-line treatment, 32.0% received CT alone, while 5.7% received CT followed by ET. In first-line treatment, 72.4% progressed on or after stopping therapy, with a median TTP of 8.4 months. In second-line treatment, 70.1% progressed, with a median TTP of 6.1 months. Disease progression was the most common reason for discontinuing both first- and second-line treatment (70.1% and 67.1%, respectively). CONCLUSIONS: Although ET is the recommended treatment for most patients with ER+/HER2– MBC, a substantial proportion received CT, possibly due to the high prevalence of visceral disease in the study population. Median TTP on current therapies is < 1 year. These findings suggest a continuing unmet need for new treatments that extend TTP.