PURPOSE: Recent development in ultrasonic Doppler instrumentation have allowed the direct noninvasive assessment of human renal artery blood flow. The authors conducted this study to assess noninvasive characterization of normal renal artery blood flow variables hopping to establish standards in normal children. METHODS: A total 97 normal Subjects(below the age 3 years) were examinated using by 2-D and doppler echocardiography. RESULTS: 1) Renal artery diameter increased with age and no difference was found between the Rt and Lt. 2) Renal blood flow increased with but the rate of increase was not constant in a 11 children, the older the children, the more variences were found in renal blood flow and no difference was noted between the Rt and Lt. 3) Pourcelot's index was not significantly different among 3 groups not between the Rt and Lt. 4) Renal artery diameter, renal arterial flow velocity integral, renal blood flow per minutes correlated with age, weight, height body surface area and weigh had the highest correlation among the physical variables. CONCLUSIONS: Authors are reporting normal renal blood flow variables in children and we hope it will be helpful for evaluationg renal hemodynamic changes.