In order to establish the predicted normal values of the systolic time intervals the duration of the systolic time intervals measured from simultaneous recordings of the electrocardiogram, the phonocardiogram and the carotid pulse tracing. The subjects studied were 160 healthy males and 160 females. The mean ages of males and females were 29 and 31 years old, respectively. The transformation period was not closely related to heart rate, and its mean values for males and females were 58 and 56 msec., respectively, and the mean for males and females combined was 57 msec. The remainder of the systolic time intervals, however, showed a significant linear and inverse relation to heart rate. Thus, based upon these data regression equations for the prediction of the normal values of electromechanical systole, left ventricular ejection time, mechinical systole, precjection period andisovolumiccontraction time for males, females, and males and females combined were obtained.