Dispersion of QT intervals has been proposed as a measure of repolarization process inhomogeneity (and thus refractority inhomogeneity) of ventricular myocardium. Recently other possible explanation of this phenomenon has been intensively discussed. According to this concept QT dispersion is explained by different projections of the heart repolarization vector. Moreover, the reproducibility of the measurement of QT dispersion is rather low as it could be influenced both by intrinsic (e.g., amplitude of the T wave or U wave) and extrinsic (e.g. noise, amplitude and time parameters of recording) factors. Only markedly prolonged QT dispersion must be therefore interpreted as a sign of the abnormal course of the repolarization. Nevertheless, according to all mentioned facts the only serious interpretation of increased QT dispersion is that it reflects unspecific repolarization changes. More precious explanation is by then not possible (and it is disputable if it ever will be).