Background: P-wave dispersion (PWD) has been reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. In the present study, we aimed to investigate PWD in patients with dilated cardiomyopathy. Method: The study population consisted of 72 patients with dilated cardiomyopathy and 72 healthy control subjects. Left atrial diameter, left ventricular end-diastolic and end-systolic diameters and left ventricular ejection fraction of all patients and control subjects were measured by means of transthoracic echocardiography. Maximum P-wave duration (Pmaximum) and minimum P-wave duration (Pminimum) were measured from the 12-lead surface electrocardiogram. PWD was calculated as the difference between Pmaximum and Pminimum. Results: Pmaximum and PWD of patients with dilated cardiomyopathy were significantly higher than those of control subjects (Pmaximum: 126 +/- 12 ms vs. 116 10 ms, PWD: 47 +/- 6 ms vs. 38 +/- 7 ms, respectively, P < 0.001 for all). However, there was no statistically significant difference between patient group and control group regarding Pminimum (79 7 ms vs. 78 6 ms, respectively, P = 0.27). Left atrial diameter was significantly higher in patients with dilated cardiomyopathy compared to control subjects (4.51 +/- 0.62 cm vs. 3.60 +/- 0.43 cm, respectively, P < 0.001). Left ventricular ejection fraction was found to be significantly lower in patients with dilated cardiomyopathy compared to control subjects (33 +/- 5% vs. 63 +/- 7%, respectively, P < 0.001). Conclusion: PWD was found to be significantly higher in patients with dilated cardiomyopathy than in healthy control subjects. (C) 2004 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.