Objective To investigate the characteristics of left and right ventricular volume and systolic function of tetralogy of Fallot(TOF)children by real-time three-dimensional echocardiography (RT-3DE).Methods Forty-five TOF children and 46 normal age-matched children were recruited in this study. Full volume imaging of left and right ventricle were obtained by RT-3DE and analyzed off-line by TomTec LV-Analysis and RV-Function.The measurements including:end-diastolic volume (LVEDV/RVEDV),end-systolic volume (LVESV/RVESV),ej ection fraction (LVEF/RVEF),peak systolic volume rate (LVPSVR/RVPSVR),stoke volume (LVSV/RVSV),cardiac output (LVCO/RVCO).And the volumetric parameters were indexed by BSA(indexed EDV,indexed SV,indexed CO).The measurements were compared between TOF group and normal group.The left and right ventricular measurements were also compared with each other within group.Results Compared with control group indexed LVEDV reduced in TOF group(P =0.000),while indexed RVEDV increased (P =0.002 ).For systolic function indexes:LVEF,RVEF, LVPSVR and RVPSVR in TOF group were both lower than that in normal group (P <0.05 ),indexed LVSV and indexed LVCO were also reduced (P <0.05 ),while indexed RVSV had no difference with normal(P >0.05)and indexed RVCO was increased (P =0.016).The volume and function comparision between left and right ventricle demonstrated:in normal group no difference were found in biventricular EDV,PSVR,SV,CO(P >0.05),except that LVEF was a litter higher than RVEF(P =0.000).In TOF group RVEDV,RVSV,RVCO were all greater than that of left ventricle(P <0.05),but RVEF was lower than LVEF(P =0.039).Conclusions In TOF group biventricular systolic function were both impaired and lost banlance between them.Under the volume and pressure overload the right ventricle improved pumping function by increasing heart rate.