Aims: Frailty is common in patients with atrial fibrillation (AF), with possible impact on therapies and outcomes. However, definitions of frailty are variable, and may not overlap with frailty perception among physicians. We evaluated the prevalence of frailty as perceived by enrolling physicians in the Edoxaban Treatment in Routine Clinical Practice for Patients With Non-Valvular AF (ETNA-AF)-Europe registry (NCT02944019), and compared it with an objective frailty assessment., Methods and Results: ETNA-AF-Europe is a prospective, multi-centre, post-authorization, observational study. There we assessed the presence of frailty according to (i) a binary subjective investigators' judgement and (ii) an objective measure, the Modified Frailty Index. Baseline data on frailty were available in 13 621/13 980 patients. Prevalence of perceived frailty was 10.6%, with high variability among participating countries and healthcare settings (range 5.9-19.6%). Conversely, only 5.0% of patients had objective frailty, with minimal variability (range 4.5-6.7%); and only <1% of patients were identified as frail by both approaches. Compared with non-frailty-perceived, perceived frail patients were older, more frequently female, and with lower body weight; conversely, objectively frail patients had more comorbidities. Non-recommended edoxaban dose regimens were more frequently prescribed in both frail patient categories., Conclusions: Physicians' perception of frailty in AF patients is variable, mainly driven by age, sex, and weight, and quite different compared with the results of an objective frailty assessment. Whatever the approach, frailty appears to be associated with non-recommended anticoagulant dosages. Whether this apparent inappropriateness influences hard outcomes remains to be assessed., Competing Interests: Conflict of interest: I.D. reports having received speaker fees from Boehringer Ingelheim, Bayer, Bristol-Myers Squibb/Pfizer, Daiichi-Sankyo, Medtronic, Boston Scientific, and Biotronik. A.B. reports being involved in research sponsored by and is a member of advisory panels and speakers’ bureau for Daiichi Sankyo, Pfizer, BMS, Bayer, and Boehringer Ingelheim. P.-E.R., M.C.M., and J.A.G.d.S. are employees of Daiichi Sankyo Europe GmbH. L.P. has received fees and honoraria from Daiichi-Sankyo, SOTIO Biotech, and Beckman-Coulter. P.K. receives research support from European Union, British Heart Foundation, Leducq Foundation, Medical Research Council (UK), and German Centre for Cardiovascular Research, from several drug and device companies active in atrial fibrillation, and has received honoraria from several such companies. He is listed as inventor on two patents held by the University of Birmingham (Atrial Fibrillation Therapy WO 2015140571, Markers for Atrial Fibrillation WO 2016012783). He is co-principal investigator of ETNA-AF-Europe. R.D.C. co-authored ESC Guidelines on Atrial Fibrillation 2010–2012; acted as a Steering Committee member and National Coordinator for Italy, and co-authored manuscripts published on APPRAISE-2, ARISTOTLE, AVERROES, ENGAGE AF-TIMI 48, and Re-DUAL PCI. R.D.C. has received fees, honoraria, and research funding from Sanofi-Aventis, Boehringer Ingelheim, Bayer, Bristol-Myers Squibb/Pfizer, Daiichi-Sankyo, Novartis, Portola, Roche, and Merck. He is co-principal investigator of ETNA-AF-Europe. All remaining authors have declared no conflicts of interest., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)