Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in clinical practice, and there is an increasing trend in its prevalence in the general population. Recent studies have demonstrated increased risk of atrial fibrillation (AF) in NAFLD. However, information on the mechanism of increased risk of AF in NAFLD is lacking. Impaired atrial conduction is an important factor in the pathophysiology of AF. We aimed to investigate atrial conduction properties in patients with NAFLD by tissue Doppler echocardiography. Fifty-nine ultrasound diagnosed NAFLD patients without clinical diagnosis of hypertension, diabetes mellitus, or cardiac disease and 22 normal subjects as controls were included in this study. Atrial conduction properties were assessed by electromechanical delay (EMD) derived from Doppler tissue echocardiography examination and P-wave dispersion (PWD) calculated from the 12-lead electrocardiogram. Inter-atrial and intra-atrial EMD intervals were significantly longer in NAFLD patients than in controls (inter-atrial EMD, 31.9 +/- 8.5 ms vs. 23.4 +/- 4.6 ms, p = 0.0001, and intra-atrial EMD, 14.3 +/- 5.2 vs. 10.2 +/- 4.0 ms, p = 0.001). Similarly, PWD was significantly higher in NAFLD patients compared with controls (49.2 +/- 6.3 ms vs. 43.3 +/- 4.2 ms, p = 0.0001). Maximum left atrial volume was also significantly higher in the NAFLD group than in controls (51 +/- 11 mL vs. 34 +/- 9 mL, p < 0.0001). This study demonstrated that atrial conduction is impaired in patients with NAFLD. Also, in a patient population of NAFLD without any clinical diagnosis of cardiac disease, diabetes, or hypertension, left atrial volume was increased compared with controls. These findings suggest impaired atrial conduction as a factor in increased risk of AF in NAFLD.