OBJECTIVES: To explore the effects of genetic testing of patients with breast cancer by Oncotype DX for decision  of further therapy and their prognosis. METHODS: Health economy model, using Cost-Utility Analysis (CUA), complemented by Budget-Impact Analysis (BIA) on public health insurance coverage in Slovakia. Markov Model (life time horizon) for BC patient management was developed, comparing diagnosis by Oncotype DX and standard diagnostic methods. Outcomes observed were decreased by number of women with chemotherapy (CT) and increased by proportion of women with hormonal treatment alone (HT) and their Recurence Score (RS, observed from test) in horizon of 10 years. Payer perspective and direct healthcare costs only, associated with breast cancer diagnoses patient management were considered in CUA and BIA for diagnosis subgroups. Discount rate of 5% was used for costs as well as outcomes. Sensitivity analysis for major complications was implemented. RESULTS: CUA for Oncotype DX vs. standard care associated with decreased proportion of CT and increased proportion of HT with cost per QALY 12 889 € and cost per LY 11 019 €. Net costs (BIA) associated with Oncotype DX for cohort of patients 1 200 are 3.92 mil. €.   CONCLUSIONS: Oncotype DX is considered cost-effective in terms of diagnoses and followed treatment of breast cancer patients. Oncologists are able to differentiate between a low or intermediate RS and a high RS using standard prognostic criteria. Provision of the actual RS changed the treatment recommendations in nearly 40% of cases, suggesting that the RS may reduce chemotherapy use.