Introduction: Direct oral anticoagulants are widely used in patients with nonvalvular atrial fibrillation (AF) to reduce the risk of stroke and systemic embolism, however, there is not enough real-world data of their effectiveness and safety in patients with worsening renal function (WRF). Xarelto post-authorization safety and effectiveness study in Japanese patients with atrial fibrillation (XAPASS) is a prospective observational post-marketing surveillance study mandated by the Japanese authority. It aims to examine safety and effectiveness of rivaroxaban in everyday clinical practice. This analysis investigated one year outcomes among patients with WRF and stable renal function (SRF) in XAPASS. Methods: One year follow-up data of 9578 patients enrolled in XAPASS were analyzed to evaluate baseline characteristics and safety/effectiveness profile among patients with WRF and SRF. WRF was defined as a decrease of more than 20% from enrollment creatinine clearance measurement at any time point during the study. SRF was defined as the absence of WRF at any time. Results: We identified 1229 patients (12.8%) with WRF and 6280 patients (65.6%) with SRF among 9578 patients. WRF patients were significantly older, and had significantly higher mean CHA 2 DS 2 -VASc score and modified HAS-BLED score compared to SRF patients. Prevalence of hypertension, congestive heart failure, ischemic stroke/transient ischemic attack, and myocardial infarction was higher in WRF patients. There was no difference in rates of major bleeding (hazard ratio (HR) 1.20; 95% confidence interval (CI) 0.75-1.90; p=0.45) or the composite endpoint of stroke, systemic embolism or myocardial infarction (HR 1.06; 95% CI 0.65-1.71; p=0.82) between patients with WRF and SRF. WRF patients experienced a higher incidence of transfusion of 2 units or more (0.46 versus 0.14 events per 100 patient-years; HR 3.19; 95% CI 1.04-9.74; p=0.03) versus SRF patients. Rates of other major bleeding subgroups defined according to ISTH criteria were similar between patients with WRF and SRF. Conclusions: WRF during rivaroxaban treatment did not significantly increase the rates of major bleeding or thromboembolic events, although it was associated with a higher incidence of transfusion of 2 units or more.