The measurement of systolic time intervals has become one of the established quantitative noninvasive tests of cardiac function, especially of left ventricular performance, and remain one of the simplest and most reliable to perform. In an attempt to obtain the normal data of the systolic time intervals, we conducted a study in 89 normal Koreans of 43 males and 46 females. The measurements are obtained from the simultaneous high speed recordings (100mm/sec) of electrocardiogram, phonocardiogram, and indirect carotid arterial pulse. The results were as follows. 1. The QS2I, LVETI, and PEPI was 521+/-18 msec, 409+/-13msec, and 112+/-12 msec in males and 529+/-14 msec, 408+/-15 msec, and 121+/-11 msec in females, respectively. 2. The PEP/LVET ratio was 0.29+/-0.04 in males and 0.31+/-0.05 in females. 3. The QS2I and PEPI were significantly more lengthened in femals than in males, but other systolic time interval indices did not significantly relate to the sex. 4. The A2D was significantly shortened with age, but other systolic time intervals did not change with age. 5. According to the regression equations of QS2, LVET, and PEP to the heart rate, QS2 and LVET related more inversely to the heart rate than PEP.