It has recently become possible to record electrical activity originating from abnormally conducting myocardium from the body surface with high - gain amplification and averaging technique. These signals, which result from delayed ventricular activation(late potentials), have been recorded in patients with documented ventricular tachyarrythmia. Several electrode lead system for detecting ventricular late potential were introduced. Pyramidal electrode lead system(PLS) is useful. Also interpretation of SAECG in the young could be of value in detecting those at risk for episodic ventricular tachycardia, but suffer from a lack of data in normal young people. Selection of subjects : For this study, normal healthy young adult volunteers (age: mean 24 years) were recruited from the medical students at Yeungnam University Hospital, Internal Medicine. Twenty fourths male and seventeenths female subjects were selected. All subjects had normal resting ECGs as judged from both the standard 12 channel lead and echocardiography, and none had a history of cardiovascular disease. All subjects were considered to be in good general physical condition. Signal-averaged electrocardiography : In order to obtain low noise recordings with a small number of averaging cycles, all subject ware asked to relax completely in the supine position. Silver/silver chloride electrodes were attached after the skin was cleaned with alcohol, to constitute classic flank lead system(FLS) and pyramidal lead system(PLS). Signals were recorded and processed using a commercially available microprocessor-augmented ECG cart(Marquette Electronics, USA) suitable for portable bedside recording. There was no difference between normal values, determined by FLS and PLS at high pass filtering of 25 Hz and 80 Hz, but significant, difference was found in HFLAD and RMS-40 of 40 Hz(p<0.05). These results will provide a basis for interpretations of SAECG, determined by FLS and PLS in healthy young adults with normal QRS duration.