Due to heightened risk for thromboembolic complications, nonvalvular atrial fibrillation (NVAF) presents an absolute indication for long-term oral anticoagulation therapy. This was an observational, analytical, randomised, one-year clinical study, conducted in the Blood Transfusion Institute Sarajevo, Bosnia & Herzegovina. The aim of this study was to present the oral anticoagulation treatment in terms of International normalised ratio (INR) monitoring and warfarin/acenocoumarol dose titration in 117 patients with NVAF. INR values, the doses of warfarin and acenocoumarol, as well as the tendency and adequacy of their changes were monitored. Percentages of the therapeutic INR values were 51,77% and 53,62%, subtherapeutic 42,84% and 35,86%, and supratherapeutic 5,39% and 10,53% for the warfarin and acenocoumarol treatment, respectively. The average total weekly doses (TWD) which most frequently achieved the therapeutic INR values were 27,89+/-12,34 mg and 20,44+/-9,94 mg, for warfarin and acenocoumarol, respectively. The dose changes with the INR values 1,7 or lower/3,3 or higher were omitted in 13,46% and 15,63%, and with the INR values 1,8-3,2 were noted in 8,62% and 13,48% of all the check-up visits in the warfarin and acenocoumarol group, respectively. The annual dose changes were noted in 24,65% and 31,41%, and the daily dose changes in 74,43% and 73,36% of all the check-up visits of warfarin and acenocoumarol group, respectively. We can conclude that the management of the oral anticoagulation treatment in our country is in accordance with the relevant recommendations, but with the present tendency toward underdosing and unnecessary frequent dose changing.