Background: Onset of atrial fibrillation in hypertensive patients is usually associated with a high occurrence of cardiovascular complications. Therefore, it is important to assess non-invasively the risk of developing paroxysmal atrial fibrillation(PAF) in hypertensive patients during sinus rhythm. This study was undertaken to determine if hypertensive patients with history of PAF could be identified while in sinus rhythm by measurement of signal-averaged ECG P-wave duration. Methods: Signal-averaged electrocardiography(SAECG) P-wave recording was performed in 44 hypertensive patients(30 men and 14 women; mean age 60±11 years, group A) who had a history of paroxysmal AF and in 50 hypertensive patients without history of AF(33 men and 17 women; mean age 57±12, group B). All patients were also evaluated by using echocardiography to measure left ventricular ejection fraction(LVEF) and left atrial diameter(LAD). Results: SAECG P-wave duration was found to be significantly higher in group A than in group B(146±14 ms vs. 128±11 ms, p< 0.001). Left atrial diameter was not significantly different(40.1±3.4 mm vs. 39.3±3.0 mm, p >0.05), whereas LVEF was significantly lower in group A than group B(63±5%vs. 67±4%, p=0.03). There was a correlation between SAECG P-wave duration and age(r=0.32, p< 0.05). In univariate analysis, SAECG P-wave duration and LVEF were significant predictors of PAF, but only SAECG P-wave duration remained a significant independent predictor of PAF in multivariate analysis. Conclusion: The results of this study indicate that hypertensive patients with history of PAF can be detected while in sinus rhythm by signal-averaged ECG P-wave duration. Background, Onset of atrial fibrillation in hypertensive patients is usually associated with a high occurrence of cardiovascular complications. Therefore, it is important to assess non-invasively the risk of developing paroxysmal atrial fibrillation (PAF) in hypertensive patients during sinus rhythm. This study was Methods: Signal-averaged electrocardiography (SAECG) P-wave recording was performed in 44 hypertensive patients (30 mean age 60 ± 11 years, group A) who had a history of paroxysmal AF and in 50 hypertensive patients without history of AF (33 men and 17 women; mean age 57 ± 12, group B). All patients were also evaluated by using echocardiography to measure left ventricular ejection fraction (LVEF) and left atrial diameter (LAD). Results: SAECG P-wave duration was found to be significantly higher in grou pA than in group B (146 ± 14 ms vs. 128 ± 11 ms, p <0.001). Left atrial diameter was not significantly different (40.1 ± 3.4 mm vs. 39.3 ± 3.0 mm, p> 0.05) significantly lower in group A than group B (63 ± 5% vs. 67 ± 4%, p = 0.03). There was a correlation between SAECG P-wave duration and age (r = 0.32, , SAECG P-wave duration and LVEF were significant predictors of PAF, but only SAECG P-wave duration remained a significant independent predictor of PAF in multivariate analysis. Conclusion: The results of this study indicate that hypertensive patients with history of PAF can be detected while in sinus rhythm by signal-averaged ECG P-wave duration.