OBJECTIVES: Atrial fibrillation (AF) is frequent cardial disease. The prevalence in Slovak republic is estimated about 1% in adult population. The most potential risk of AF is stroke, Ist incidence is estimated about 2.3% e.g. more than six times as in standard population. The main objective of this study was to determine direct medical costs related to AF and the possible budget impact of new treatment by dronedaron. METHODS: Direct medical costs were evaluated from data collected in 2007 from the General Health Insurance Company, the largest one in Slovakia, covering 55% of 5.4 million inhabitants. The results were recalculated to the total population. The costs were quoted in 2007 prices.RESULTS:   The AF costs were €16,685,720; in out-patients care they were €1,384,743; in hospital care they were €12,135,196; in drug consumption they were  €2,013,127  and in diagnostic procedures  they were €1,152,653.  Totally it was 0,556% of total Slovakia health care budget. The cost of treating the patients with stroke was €30,098,891, which is 1.003% of total Slovakia health care budget. Dronedaron is new drug for the treatment of AF. The outcomes from the ATHENA study showed 26% risk reduction of hospitalization and 34% risk reduction of stroke.  The dronedaron usage can reduce the health care costs by €2,872,370 per year, i.e. 0.096% from total budget. CONCLUSIONS: The direct costs associated with AF comprise an important part of total health care budget in Slovakia. They signalize the need to establish effective strategies for AF. Clinical outcomes from the ATHENA study adapted  to Slovak conditions show the actual potential of dronedaron to be a cost-effective way in reducing AF complications and decreasing health care expenditures.