Breast cancer is the most common type of cancer in women and is also the leading cause of death in women suffering from malignant illnesses. According to Globocan data from 2012, 1.7 million women have developed breast cancer and 522,000 died from it. It is estimated that the incidence of breast cancer has increased by more than 20% and mortality by 14% since 2008. According to the Croatian National Cancer Registry of Croatian Institute of Public Health (Registar za rak Hrvatskog zavoda za javno zdravstvo) for 2015, with a rate of 26% among all cancer sites, breast cancer is the most common type of cancer in women in the Republic of Croatia. In 2015, 2748 women developed breast cancer in the Republic of Croatia. The incidence of breast cancer as well as mortality are increasing worldwide, except in highly developed countries where the mortality rate has been declining. Breast cancer is one of the leading public health problems of developed Western countries because one in eight women develops breast cancer. Despite the progress of diagnostics and therapy, a significant number of women sill die from this disease. Various clinical outcomes and response to therapy depend on biological diversity in tumors. Personalized therapy in treating breast cancer improves the outcome of the treatment. Despite the progress in diagnostics and treatment of breast cancer patients, the occurrence of distant metastases is still frequent. In 20 to 30% of patients with early stages of breast cancer, incidence of distant metastases is observed. The risk of recurrence depends on the biological characteristics of the tumor and the stage of the disease. Tumor size, lymph node involvement, hormone receptor status and receptor expression of the human epidermal growth factor receptor 2 are various independent prognostic factors of recurrence. One of the etiological factors is the activation of the HER-2/neu proto-oncogene. The finding of HER-2 has a prognostic and predictive value, occurs in 15 to 20% of early stage breast cancers and correlates with more aggressive tumor behavior. Such a finding correlates with a poorer response to antihormonal treatment. Excessive expression of HER-2 protein is considered only as a 3+ finding, which results in a diffuse, highly positive membrane coloration and is an indication for treatment with anti HER-2 therapy. Metastases at distant organ sites are generally considered incurable and are the cause of most cancer-related deaths. HER-2 positive breast cancers are more likely to metastasize to visceral organs, predominantly liver, lungs, brain and bone. In the first-line treatment of the metastatic HER-2 positive breast cancer, a combination of anti HER-2 and cytostatic therapy or anti HER-2 and hormone therapy is administered. The paper analyzes the number and type of first-line treatment in patients with metastatic HER-2 positive breast cancer during 2015 and 2016 in Clinical Hospital Center Rijeka (KBC Rijeka). Since December 2015, in addition to taxanes, the Croatian Health Insurance Fund (HZZO) approved the dual anti-HER2 therapy (trastuzumab and pertuzumab). According to recommendations of the Fund (HZZO), up to 2015, the routine clinical practice included treatment with taxanes and trastuzumab only. The paper analyzes the number of cycles applied until the progression of the disease, ie the completion of the monitoring. An analysis and comparison of the financial cost of treatment for the period of two years of anti-HER2 therapy administered to the patients at the Clinic for Radiotherapy and Oncology was made.