An automatic procedure for the pre-processing of ECG/VCG signals has been implemented on a HP2100 computer in order to test the significance of a few algorithms for the reduction of low-frequency and high-frequency noises superimposed on the tracings, i.e. baseline-drift evaluation and correction, low-pass and high-pass analogue and digital filterings. It is shown that such operations diminish the influence of noise and improve the phase of feature extraction in the processing program for a better measurement of wave amplitudes, durations and intervals. Such aspects are considered fundamental due to the increasing applications of 24-h Holter type recording, microprocessor-based modules both in the cardiological field and in patient monitoring systems, besides taking into account the new design concept of electrocardiographic equipments which, in the future, will become more and more a sort of data acquisition modules.