Background-Despite its therapeutic efficacy, warfarin is extremely underused in Chinese patients with nonvalvular atrial fibrillation (AF). Whether the nonpersistence of warfarin treatment contributes to its underuse is not known. The aims of this study were to determine nonpersistence rates of newly started warfarin treatment in Chinese patients with nonvalvular AF and to identify the factors associated with discontinuation of the treatment. Methods and Results-We identified 1461 patients with nonvalvular AF enrolled in the Chinese Atrial Fibrillation Registry (CAFR) who newly started on warfarin therapy in the period between August 1, 2011, and June 30, 2014. During a follow-up of 426 +/- 232 days, 22.1% of patients discontinued warfarin within 3 months, 44.4% within 1 year, and 57.6% within 2 years of initiation of therapy. Patients with no or partial insurance coverage had a higher likelihood to discontinue warfarin than those with full insurance coverage (adjusted hazard ratio 1.65, 95% confidence interval [1.03-2.64]; P=0.038 and 1.66 [1.13-2.42]; P=0.009, respectively). Paroxysmal AF (1.56 [1.28-1.92]; P<0.0001), no prior stroke/transient ischemic attack/thromboembolism (1.60 [1.24-2.05]; P=0.0003), and no dyslipidemia (1.34 [1.06-1.70]; P=0.016) were also found to be independent predictors for nonpersistence of warfarin therapy. Conclusions-Nonpersistence of warfarin treatment becomes a serious problem for stroke prevention in Chinese patients with nonvalvular AF. Our findings can be used to identify patients who require closer attention or to develop better management strategy for oral anticoagulation therapy.