Objective: P-wave dispersion (Pd), defined as the difference between the maximum and the minimum P-wave duration (Pmin), and maximum P-wave duration (Pmax) are electrocardiographic (ECG) markers that have been used to evaluate the discontinuous propagation of sinus impulses and the prolongation of atrial conduction time, respectively. The incidence of cardiac arrhythmias, particularly atrial fibrillation (AF), following acute alcohol intake has been previously reported. Prolonged P-wave duration and Pd have been reported to represent an increased risk for AF. However, the association between Pd and acute alcohol intake has not been studied previously in normal subjects. Methods: In a randomized crossover study, 10 healthy male volunteers, aged 30.0 ± 2.1 years (range 25-33) received either ethanol and/or placebo (juice). Alcohol group drank moderate dose ethanol; 0.97 ± 0.12 g/kg body weight (range 0.80-1.25 g/kg), and the other group consumed same amount of juice in one-hour period. After 48-hours washout period, alcohol group took juice and juice group drank alcohol. Pmax, Pmin and Pd were measured as milliseconds (ms) on baseline ECG, after alcohol period (AP) and after juice period (JP). Results: In comparison with baseline, Pmax values were significantly prolonged after AP but not after JP (baseline: 95.3 ± 5.3 ms, after AP: 103.7 ± 9.5 ms, after JP: 94 ± 7 ms, p=0.027, p=0.102, respectively). Pmin values did not change significantly. And also, in comparison with baseline, Pd values were significantly prolonged after AP but not after JP (baseline: 27.0 ± 7.6 ms, after AP: 42.7 ± 12.8 ms, after JP: 27.0 ± 6.7 ms, p=0.021, p=0.891, respectively). Conclusion: Acute moderate dose of alcohol intake in short time is associated with an increase in Pmax and Pd