Dynamic observations on systolic time intervals (STIs) have been undertaken in 24 children with ventricular septal defect (VSD), in 16 with atrial septal defect (ASD) and in 12 with tetralogy of Fallot (TF) before and after radical surgery by simultaneous recording of electrocardiogram, phonocardiogram and carotid pulse tracing. In comparison with the STIs in normal children, the left ventricular ejection time index (LVETI) was significantly shortened, the pre-ejection period index (PEPI) significantly prolonged, and the ratio index of PEP to LVET (PEPI/LVETI) and that of isovolumic contraction time (ICT) to LVET (ICTI/LVETI) were significantly increased in the three groups of congenital heart disease before surgery, indicating definite impairment of the left ventricular performance. The dynamic changes after surgery were: In VSD, the abnormal degree of STIs was even greater at the early postoperative period for about 2–3 weeks, and since then it became improved gradually and nearly normal at the 7th-10th months. In ASD, STIs promptly became entirely normal at the 2nd-3rd weeks after surgery. In TF, STIs became approximately normal at the 2nd-3rd weeks after surgery, and were entirely normal at the 3rd-4th months. The changes of STIs after surgery were chiefly related to the improvement of hemodynamics. The left ventricular performance became normal much more slowly in VSD than in ASD and TF, and the reason was probably that left ventricular hypertrophy was present with impairment of myocardial contractility in the former. The measurements of STIs can sensitively reflect the dynamic changes of the left ventricular performance in children with VSD, ASD and TF before and after radical surgery, and can be used to monitor the state of the left ventricular performance after surgery to provide useful information for the evaluation of the effects of surgery and for supervision of the physical activity of the children during convalescense.