PURPOSE: To evaluate the blood flow velocity waveform of the renal artery and renal volume of growth-retarded fetuses and to compare them with those of normal fetuses. MATERIALS and METHODS: Pulsatility index of the renal artery and renal volume measured by three-dimensional ultrasonography were obtained from seventy eight normal fetuses at the gestational age from twenty five to thirty nine weeks and eighteen intrauterine growth retarded fetuses whose weight was below ten percentile at birth. We studied changes of the pulsatility index of the renal artery and renal volume according to the gestational age and compared with those of growth-retarded fetuses. RESULTS: Pulsatility index(PI) of the fetal renal artery decreased throughout the gestational period (r=-0.703, p 0.0001). In growth-retarded fetuses, despite of abnormal doppler velocity waveform of the middle cerebral artery, which was showing fetal hypoxia, the renal PI was not increased significantly. The fetal renal volume increased throughout the gestational period (r= 0.834, p <0.0001) whereas in growth-retarded fetuses, all renal volume was below fifth percentile of normal fetuses. CONCLUSION: In growth-retarded fetuses, fetal renal volume was decreased significantly without change of the renalvascular flow. Therefore, the fetal renal volume measured by three-dimensional ultrasonography may be a helpful parameter in the diagnosis of growth-retarded fetus.