Background and Objectives: P-wave dispersion (PWD) is a well-known electrophysiological parameter of atria prone to fibrillation. The occurrence of paroxysmal atrial fibrillation (PAF) following acute myocardial infarction (AMI) is not uncommon. But, the relationship between the PWD and PAF following AMI has not yet been investigated. Subjects and Methods: we reviewed electrocardiographies, recorded on admission and every day during hospitalization, of 144 patients with first anterior AMI and measured P-wave duration. We inspected the left atrial diameter and left ventricular ejection fraction (LVEF) evaluated by echocardiography. Results: We found that PAF occurred in 20 patients. Maximum P-wave duration and PWD were found to be significantly higher in patients with PAF than those without PAF (120.1 짹 8.6 vs 109.2 짹 12.2 ms, p<0.001; 68.5 짹 11.9 vs 48.7 짹 9.6 ms, p<0.001, respectively). Minimum P-wave duration was significantly lower in patients with PAF than in patients without PAF (51.6 짹 13.3 vs 60.4 짹 11.7 ms, p = 0.003). There was no significant difference in the left atrial diameter (37.3 짹 4.4 vs 36.8 짹 5.1 mm, p=0.652), however, LVEF was found to be significantly different in the patients who developed PAF and in those who did not (38.5 짹 11.4 vs 45.1 짹 8.7 %, p=0.003). Conclusion: Maximum P-wave duration and P-wave dispersion could be significant predictive factors of PAF in patients with anterior wall ST elevation AMI in univariate analysis. On the basis of multivariate anlalysis, age was independent predictive parameter for PAF, as well.