OBJECTIVES Identify treatment patterns of care and the associated costs of metastatic breast cancer (MBC) treatment from the Brazilian private health care system (BPS) perspective. METHODS A cross-sectional chart review study with data collection from a private oncology clinic in Rio Janeiro. From the clinic, medical charts for 32 patients with MBC who received systemic cancer treatment between 2000 and 2007 with at least 1 year of follow-up were reviewed. RESULTS The average age was 56 years (33 to 73 years old) with 30% HER-2 positive, and 65% hormone receptor positive. First line treatments most frequently received were docetaxel (23%), gemcitabine+cisplatin (13%) and paclitaxel (13%). The most common second line treatment (81% of patients received second line) were docetaxel (16%), gemcitabine+cisplatin (16%), and paclitaxel (16%). The median number of lines of treatment received was 3 (range: 1 to 8). Resource utilization (per month) included 1.70 outpatient visits (SD:1.22), 0.22 plain thorax x-rays (SD:0.29), 0.15 thorax CTs (SD:0.24) and 0.14 abdominal US (SD:0.22). The average duration of treatment was 16.0 months (SD:11.6). The average costs for drugs/materials, outpatients visits and exams were R$106,511, R$853 and R$3,147, respectively. On average, first line treatment for a MBC patient costs R$39,367 (SD: R$38,121), with an average treatment duration of 5.12 months (SD:3.96). The average treatment costs for second line treatment, with an average duration of 5.08 months (SD:3.23) is R$ 52.040 (SD: R$51,328). From the study cohort, the main types of insurance were: medical group (HMO-like) (41%) and insurance company (28%). The higher costs per patients were for those covered under insurance companies (R$144,432) and lower costs with Medical Cooperatives (UNIMEDs - R$93,771). CONCLUSIONS Patients with MBC followed for at least one year following MBC diagnosis, result in an average cost of care of R$ 110,512 for the Brazilian private health care system.