The application of local interpolation techniques to improve the measurement of ambulatory electrocardiogram (ECG) parameters is discussed. The method allows the processing of the ambulatory ECG data using low sampling rates and obtains reasonably accurate measurements of the QRS complex. The ECG parameters were measured using both uninterpolated and interpolated data. it was found that the results obtained with local interpolation were closer to the actual values. The added execution time per beat was 16 mu s, which is about 12% of the average time to analyze a beat at the normal heart rate of 72 and a playback speed of 100 times the real time. The improvement in classification accuracy is believed to justify the added processing time. >