Oral anticoagulants are widely used to prevent and treat thromboembolic disorders, but inappropriate use can increase adverse effects and reduce therapeutic efficacy. This study evaluated the utilization patterns, dosing appropriateness, and adverse effects of oral anticoagulants in a tertiary hospital in Iran. A retrospective cross-sectional study was conducted at Razi Educational Hospital, Birjand University of Medical Sciences, from April 2020 to September 2022. Data were collected from medical records and pharmacy databases for patients aged ≥18 years who received warfarin, rivaroxaban, or apixaban. Dosing appropriateness was assessed using 2021 European Heart Rhythm Association (EHRA) and UpToDate guidelines, while adverse effects were classified according to 2020 American College of Cardiology (ACC) criteria. Among 1,027 patients (mean age 64±16.4 years; 52.3% male), rivaroxaban was the most prescribed anticoagulant (43.5%), followed by warfarin (33.2%) and apixaban (23.3%).Warfarin was primarily used for valvular heart disease, whereas DOACs were mainly prescribed for non-valvular atrial fibrillation and venous thromboembolism. Adverse effects occurred in 12.1% of patients, mostly minor bleeding, with warfarin accounting for the majority. Guideline-based dosing was achieved in 61.9% of apixaban and 58.6% of rivaroxaban users; 46.9% of warfarin patients reached therapeutic INR (2-3). Correct renal dose adjustments were applied in 40.5% of apixaban and 33% of rivaroxaban users. Guideline adherence for oral anticoagulant dosing was suboptimal. Improved prescriber education, enhanced drug utilization evaluation, and routine renal monitoring may enhance patient safety and optimize anticoagulation outcomes.