OBJECTIVES:  Ovarian cancer (OC) is a rare disease but an important cause of cancer mortality in women in Spain (4.8%). 90% are epithelial OC and 70% are high-grade serous OC (HGSOC). Approximately 20% of HGSOC are BRCA1/2 mutated (BRCAm). Despite advances in treatment, 70%-80% of epithelial OC patients relapse after surgery and first-line platinum-based chemotherapy requiring further treatment. Olaparib is the first PARP inhibitor approved and the only oral maintenance therapy for platinum-sensitive relapsed (PSR) BRCAm HGSOC patients. Olaparib has shown to delay progression and thus the need for subsequent chemotherapies. The aim of this study is to estimate the economic impact of olaparib in those patients in Spain. METHODS:  From an initial number of patients, based on Spanish published OC epidemiology data (prevalence for year 1 and incidence for years 1 to 5), a patient flow is used to get the target population of olaparib. Target patients are distributed through a decision tree model within four lines of treatment during a 5-year time horizon. We use clinical trials Kaplan Meier survivals curves to model treatment durations. The model considered direct costs as chemotherapy and maintenance drugs, genetic test and administration costs (€2015). RESULTS:  Olaparib uptake is associated with a potential patient increase in second line due to olaparib longer PFS. The budget impact on the National Health System (NHS) ranging from €1.6M to €5.6M (1-5 years). The total NHS oncology drugs expenditure was €2,944M in 2015, therefore, olaparib introduction would represent 0.05% of expenditure in the first year and 0.19% five years later. CONCLUSIONS:  The introduction of olaparib as maintenance treatment in the PSR BRCAm HGSOC patients has a manageable budget impact in Spain and suggest that it it could increase PFS and delay subsequent chemotherapy.