INTRODUCTION: HER2-positive metastatic breast cancer (mBC) is an incurable disease associated with years of chronic therapy and excess cost. HER2-targeted therapies have shown survival benefit for early-stage and mBC; however, the economic impact of these therapies has not been fully assessed. We evaluated health care resource use (HCRU) and costs of mBC patients treated with HER2-targeted therapy. METHODS: This was a retrospective cohort study using the IQVIA Real-World Data Adjudicated Claims Database (July 1, 2014 to July 31, 2019). Female patients aged ≥18 years with mBC who initiated HER2-targeted therapy in the prior year were identified. The index date was the initiation date of the HER2-targeted agent, after which patients were required to have ≥12 months of follow-up. Annual and cumulative all-cause and BC-related costs (2019 USD) and annual BC-related HCRU were computed in years 1, 2, and 3 following the index date. RESULTS: Following the initiation of HER2-targeted therapy, the mean annual total all-cause costs per patient in years 1 (n = 423), 2 (n = 357), and 3 (n = 166) were $320,892 (SD: $224,343), $235,159 (SD: $185,287), and $226,254 (SD: $197,901), respectively. The mean annual total BC-related costs were $240,048 (SD: $151,230), $175,631 (SD: $148,058), and $165,506 (SD: $159,374) in years 1, 2, and 3, respectively. A major portion of BC-related costs were costs associated with HER2-targeted treatment. The 3-year cumulative all-cause and BC-related total costs were $769,573 (SD: $456,920) and $624,455 (SD: $401,319), respectively. CONCLUSION: Treatment of HER2-positive mBC is a substantial economic burden. A potential approach to minimizing cost and HCRU is to prevent recurrence.