Left ventricular (LV) hypertrophy at electrocardiography (ECG) predicts incident atrial fibrillation (AF). However, the diagnostic performance of ECG for diagnosis of LV hypertrophy in patients with AF is still not well characterized. We analyzed 563 hypertensive patients enrolled in the Umbria-Atrial Fibrillation (Umbria-FA) registry, an ongoing prospective observational registry in patients with AF. All patients underwent ECG and standard echocardiography at their entry in the Register. Mean age was 74 years and 43% of patients were women. Prevalence of ECG-LV hypertrophy, defined by Perugia criterion corrected for body mass index, was 23%. Echocardiographic LV mass was the reference standard. Sensitivity, specificity and diagnostic accuracy of ECG-LV hypertrophy were 37.4% (95% confidence interval [CI]: 31.6-43.4), 90.0% (95% CI: 86.0-93.2) and 64.5% (95% CI: 60.4-68.3), respectively. Performance was comparable in patients with AF or sinus rhythm at ECG recording. The area under the receiver-operating characteristic (ROC) curve was 0.622 (95% CI: 0.580-0.664) in the group with AF and 0.662 (95% CI: 0.605-0.720) in that with sinus rhythm (p ​= ​0.266 for comparison). These data suggest that standard ECG is reliable for diagnosis of LV hypertrophy in patients with a history of AF, regardless of the presence of AF or sinus rhythm at the time of ECG recording.