Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. It can be associated with mortality, largely due to its thromboembolic complications. Disabling stroke is the most severe of them. Some of the research sugest that appropriate anticoagulant therapy (VKA and NOAC) reduces the risk of thromboembolism by two thirds. The relevant data was collected from 743 patients with nonvalvular, previously diagnosed AF being referred to KBC Zagreb from all the regions of Croatia. It was hypothesized that the therapeutic effect of anticoagulant drugs corresponds with adequate therapeutic recommendationand the ESC guidelines. The obtained results were in many ways unexpected. Total 75.5% of patients had adequate therapy recommendation (VKA and NOAC), but only 31.4% of them had a PT-INR value within recommended therapeutic range. Therfore, according to the treatment recommendation we are in front of the much more developed regions, such as North America and Western Europe, but due to the therapeutic effect we are behind Indica and China. Also, patients with other comorbidities, such as HA, DM and those with HAS-BLED score ≥ 3 are more often inadequately anticoagulated. The conclusion is that the effectiveness of pharmacological prevention of thromboembolic complications of AF in Croatia lags significantly behind the results shown in Western countries, but also offers the clues how and where to improve the treatment strategies.