['We hypothesized that P-wave amplitude in lead I is related to left atrial (LA) remodelling and inter-atrial conduction pattern, and has a predictive value for recurrence after radiofrequency catheter ablation (RFCA) among patients with paroxysmal atrial fibrillation (PAF).', 'A total of 525 consecutive patients with PAF (76% male, 56 ± 12 years old) who underwent RFCA were included. We compared pre-procedural sinus rhythm electrocardiograms without antiarrhythmic drug effect with LA volume (CT), LA voltage (NavX), the earliest activation site (EAS) conduction pattern of LA, and clinical recurrence rate. P-wave amplitude in lead I was significantly lower in patients with recurrence than in those that remained in sinus rhythm (P < 0.001) during 21 ± 10-month follow-up. P-wave amplitude in lead I was linearly correlated with LA voltage (β = 2.52, 95% CI 0.606-4.425, P = 0.010), LA conduction velocity (β = 1.91, 95% CI 0.941-2.876, P < 0.001), and low septal displacement of EAS (β = -1.67, 95% CI -2.352 to -0.996, P < 0.001). P-wave amplitudes <0.1 mV in lead I were independently associated with clinical recurrence of AF on multivariate Cox regression analysis (adjusted HR 2.163, 95% CI 1.307-3.581, P = 0.003). The integrated area under the curves was 0.705 (95% CI 0.655-0.755).'] Is low P-wave amplitude ( < 0.1 mV ) in lead I associated with displaced inter-atrial conduction and clinical recurrence of paroxysmal atrial fibrillation after radiofrequency catheter ablation?