The authors examine the feasibility of analyzing high fidelity electrocardiograms (ECGs) recorded during exercise tests to study changes that occur in the high frequency region (150 Hz-250 Hz) of the QRS complex. High fidelity ECGs from the V3, V4, V5, and V6 chest leads were analyzed before, during, and after exercise tests from five patients with arteriographically proven coronary artery disease, and from four normal subjects. The ECG signal was averaged to reduce the uncorrelated noise level, and filtered by a 150 Hz-250 Hz bandpass filter. The resultant high frequency ECGs from the different stages of the exercise test were examined for the root mean square (RMS) voltage over the QRS. Each RMS value obtained during peak exercise was normalized by the value obtained at rest. It was found that in the coronary artery disease (CAD) patients the normalized RMS values in leads V4, V5, V6 were significantly lower than the normalized RMS values obtained from normal subjects.