While analyzing ventricular repolarization in accordance with the invention, ECG measurement with excitation of heart rate is evaluated and the coupling of an internal parameter, for example QT to heartbeat interval, for example RR, is modeled by a transfer function with three parameters. The values of the resulting five parameters describing the static and dynamic characteristics of ventricular repolarization are obtained by means of transfer function parameters and the measured values of heart rate and the internal parameter. The effect of medication is evaluated from the difference of the values of these parameters determined before and after administrating the medication.