Objectives: The primary goal is to show progression-free survival in the first line of treatment. Secondary goals are: progression-free survival in the second line of treatment, post-progressive survival and overall survival in patients with metastatic HER 2 positive breast cancer treated at the Clinic for Oncology and Radiotherapy University Hospital of Split in the period from 2016 to 2020, and obtained compare the results with data from the available world literature. Subjects and methods: A retrospective analysis was done from the database collected data on 35 patients who were diagnosed with metastatic HER 2 positive breast cancer in the period from the beginning of 2016 to the end of 2020, either as an initial metastatic disease or after previous treatment for breast cancer. The database includes demographic characteristics of patients and pathohistological and clinical characteristics of tumors. The database was closed on May 15, 2021. Results: No significant difference was found between the incidence of new metastatic diseases and metastatic diseases after previous breast cancer treatment. The most common immunophenotype is the HER 2 luminal type. Patients usually have only one site of metastasis. Significantly more often patients have parenchymal metastasis. The median progression-free survival in the first line is 21.5 months. The median progression-free survival in the second line is 11.2 months. The median postprogestion survival is 13 months. The median overall survival was not reached. Conclusion: The treatment outcomes of patients with metastatic HER 2 positive breast cancer treated at the Clinic for Oncology and Radiotherapy, University Hospital of Split are comparable to the results of registration clinical studies.