The post-marketing Drug Use Results Survey of bepridil hydrochloride hydrate tablets (Bepricor(R) Tablets : Bepridil) in persistent atrial fibrillation was conducted from May 2009 through June 2012. We enrolled treatment-naïve patients with persistent atrial fibrillation lasting at least 7 days for which other antiarrhythmic drugs were unavailable or ineffective using prospective central registration method. The observation period was 12 weeks and additional follow-up up to 52 weeks in total was conducted for patients who completed the 12 weeks administration. We collected 501 cases from 97 medical institutions, and 496 and 450 cases in the safety and efficacy analysis sets, respectively, were subject to analysis after exclusion. The observation period (period of administration) for the safety analysis set was 267.5±128.5 days (Mean±SD). The incidence of adverse drug reactions (ADRs) was 19.6% (97 out of 496 patients) in the safety analysis set during the period of this survey. The most frequently reported ADRs were “electrocardiogram QT prolonged” (57 patients, 11.5%), “hepatic function abnormal” (8 patients, 1.6%), bradycardia (5 patients, 1.0%), and liver disorder, renal impairment, malaise and hypotension (3 patients each, 0.6%). Torsades de pointes occurred in 2 patients (0.4%), was mild in severity in both patients, and its outcome was “recovering” or “ recovered” . Interstitial lung disease occurred in one patient (0.2%) and its outcome was “recovered with sequel” . Other serious cardiac system ADRs were atrial flutter, cardiac arrest, sick sinus syndrome, sinus arrest (1 patient each, 0.2%). all of them were recovering or recovered. Though cardiac failure (exacerbation of heart failure) occurred in 2 patients (0.4%), it was non-serious in both patients and resolved. As for efficacy, “effective” was defined as at least 1 observation of sinus rhythm in the observation period after the onset of bepridil therapy up to 52 weeks. The proportion of “effective” cases in the efficacy analysis set was 59.6% (268/450) and that of the cases remaining in sinus rhythm through observation was 66.8% (179/268). As indicated above, no concern about efficacy was observed in this survey. Regarding safety, although no new issues were identified, it was confirmed that strict compliance to the approved “dosage and administration” and “precautions for use” in the physicians circular is important to prevent the occurrence of serious ADRs.