Background: Human epidermal growth factor receptor 2 (HER-2) overexpression can be found in 15-20% of breast cancers, and it strongly correlates with aggressive clinical behavior and adverse prognosis. The first-line treatment for HER-2 positive metastatic breast cancers is the combination of trastuzumab, pertuzumab, and taxane (PTH). ABP 980 is a biosimilar of the innovator trastuzumab and is characterized by highly comparable effectiveness. Methods: The group of 61 patients with HER-2 positive MBC received biosimilar ABP 980 plus pertuzumab and docetaxel from November, 18, 2018 to December, 24, 2019. The response to therapy, overall survival (OS), progression-free survival (PFS), metastases, and adverse effects among patients were determined and analyzed. Results: Initially, 42 women responded partially to the treatment and their median PFS was 27 months. Median PFS for the whole group was 18 months. Cardiotoxicity of treatment was noticed in all patients in the form of the reduction in left ventricular ejection fraction but only in 2 cases, it was the reason for withdrawing from therapy. Conclusion: Biosimilar ABP 980 is registered in the same indications as the innovator trastuzumab and their effectiveness, as well as side effects, are comparable. The costs of biosimilar make the therapy more accessible and thus more patients with MBC around the world can receive relevant treatment.