Atrial fibrillation is a risk factor for ischemic stroke. To prevent stroke oral anticoagulants can be administered. Old and new types of anticoagulants are available. Nowadays, old type, acenocumarol based anticoagulants are used preferentially in Hungary. Aim: The advantages and the disadvantages of anticoagulants are well known, but anticoagulants are underused in many cases. Method: The authors retrospectively examined how frequent atrial fibrillation was and whether the usage of anticoagulants in practice was in accordance with current guidelines among acute stroke cases admitted to the Department of Neurology, Medical and Health Science Centre of Debrecen University in 2009. Results: Of the 461 acute stroke cases, 96 patients had known and 22 patients had newly discovered atrial fibrillation. Half of the patients did not receive proper anticoagulation. Only 8.4% of them had their INR levels within the therapeutic range. Conclusions: The findings are similar to those reported in other studies. Many factors may contribute to the high proportion of improper use of anticoagulants, and further investigations are needed to determine these factors. In any case, elimination of these factors leading to a failure of anticoagulation may decrease the incidence of stroke. Orv. Hetil., 2012, 153, 732–736.