Background: The use of non-vitamin K antagonist oral anticoagulants (NOACs) in patients with non-valvular atrial fibrillation (AF) has been increasing. Accordingly, the combined use of antiplatelet agents (APT) and NOAC therapy is commonly encountered in clinical practice. The purpose of this study was to compare the clinical outcomes between combination therapy (NOAC and APT) vs. monotherapy (NOAC only) in patients with AF. Methods: We retrospectively analyzed patients who were prescribed NOACs between January 2012 and December 2016. The primary outcome was major bleeding and any bleeding events, and the secondary outcomes were stroke/systemic embolic (SE) events and major adverse cardiac events (MACE). Results: Of the 1068 participants, there were 264 (24.7%) patients in the combination therapy group. The prevalence of diabetes (p = 0.017) and history of stroke and transient ischemic attacks (p 0.001) was higher in the combination group than in the monotherapy group. During the mean 14.6 \pm 9.8 months of follow-up, the incidence of any bleeding was significantly higher in the combination therapy group than in the monotherapy group (p 0.001). The rate of major bleeding, stroke/SE, and MACE between the two groups was similar. The rate of under-dosage NOAC prescriptions was higher in the combination therapy group than in the monotherapy group (p = 0.024). Conclusions: The combination therapy group had higher incidences of any bleeding events compared to the monotherapy in patients with appropriate dosing. However, there was no difference in stroke/SE, and MACE. The bleeding risk in AF patients taking the combination of NOACs and APT should be carefully evaluated.