Aim. To present potentials of electrocardiographic (ECG) research method in the diagnosis of paroxysmal tachycardia, as well as in the presence of additional conduction pathways (DPP). To demonstrate potentials of a trivial method for identification of the type of arrhythmia, the mechanism of occurrence, and topics of the additional conduction pathway in Wolf-Parkinson-White syndrome on a clinical example. Conclusion. A widely available routine method of the ECG allows to determine the nature of arrhythmia, to choose the treatment tactics, to assess the prognosis of the disease, prior to performing complex invasive procedures.