OBJECTIVES: To describe the utilization of chemotherapy agents administered to women with a diagnosis of breast cancer, by stage of disease. METHODS: Chemotherapy utilization was extracted from two databases with population-level coverage [New Drug Funding Program (NDFP) and Activity Level Reporting (ALR) data] for women diagnosed with breast cancer between January 1, 2005 and December 31, 2009 and resident in Ontario, Canada. NDFP included expensive antineoplastics.  ALR included only intravenous antineoplastics for agents administered at cancer centres. Each entry in the database represented one exposure to an antineoplastic medication administered and funded by the province. Hormonal therapies were not included in this analysis. All duplicate entries (same patient, same drug, same date of administration, same dose) were excluded.  Overall utilization and utilization by stage of disease were determined. Chemotherapy regimen utilization was not analyzed, only individual drug use was. RESULTS: There were 39,656 breast cancer cases (34.4% Stage I; 31.8% Stage II; 12.0% Stage III; 3.9% Stage IV; 17.9% Unstaged) with a mean age of 61.6 ± 14.0 years.  Among all cases (staged and unstaged), 17,383 (43.8%) received chemotherapy.  The most common drugs administered across the entire cohort were cyclophosphamide (68.4%), docetaxel (52.8%), epirubicin (47.3%), fluorouracil (36.2%), doxorubicin (31.6%) and traztuzumab (24.3%). The drug utilization for Stage I/II was cyclophosphamide (72.9%), docetaxel (52.0%), epirubicin (49.6%), fluorouracil (37.9%), doxorubicin (31.2%), paclitaxel (23.0%) and traztuzumab (22.8%).  For Stage III/IV utilization was as follows: cyclosphosphamide (68.3%), docetaxel (62.4%), epirubicin (45.6%), doxorubicin (36.1%), traztuzumab (27.8%) and paclitaxel (26.0%).  CONCLUSIONS: This frequency distribution of chemotherapeutic agents provides population level data on the management of breast cancer, by stage. Future work will involve costing of these medications from a population perspective.