Objective To explore the value of maximun P wave duration (P max ) and P wave dispersion (P d),that is,the difference between the maximum and minimun P wave duration in patients with idiopathic paroxysmal atrial fibrillation.Methods P max and P d were measured from 12 lead surface electrocardiogram among 20 patients with a history of idiopathic paroxysmal atrial fibrillation and 20 age matched healthy control subjects.Results P max and P d were found to be significantly higher in patients with a history of idiopathic paroxysmal atrial fibrillation than in the control subjects(P