Background The P wave dispersion concept was created to describe the non-uniform atrial conduction as a separate AF factor. However the major assumptions of the theory are inconsistent with the main principle of electrocardiography, which assumes that 12 leads of ECG, recorded simultaneously, register the same events at the same time. The presence of dispersion suggests the presence of a P wave in one lead, while in the other one it has ended and no longer exists. This observation per se could be considered as a methodological artifact. Objective The major objective is to present that the P wave dispersion descends from imprecise measurements in various ECG leads. We intend to demonstrate that more accurate measurements make this parameter disappear. Methods Our study included 150 patients (89F, 61M) assessed using the electrophysiological system, which allowed to assess the sinus P waves. The P wave duration was measured by 3 independent researchers in all leads twice: 1. paper speed=50 mm/s, enhancement 16x (basic measurement) 2. paper speed=200 mm/s, enhancement 128–256x, simultaneously measuring the P wave dispersion. All measurements were repeated 3 times. Results The results are presented in Table 1 Conclusion 1. The P wave dispersion is the artifact of measurement. It is clear that after using much more accurate tools, the parameter disappears. 2. The P-wave dispersion is connected with Pmax, therefore may be apparently clinically useful but as a matter of fact, doesn't carry any meaning itself. 3.The significant P wave duration parameter should be a total atrial activation time, from the beginning of the earliest recorded P wave, till the end of the last Pwave recorded in any lead. Funding Acknowledgement Type of funding source: None