This study was performed to determine whether power Doppler sonography is superior to color Doppler sonography in the depiction of the normal fetal intrarenal vasculature during pregnancy. Twenty-five fetal kidneys in 22 healthy fetuses between 22 and 40 weeks of gestation (mean 32.6 weeks) were studied with color and power Doppler sonography with a 3.75 MHz transducer. The efficacy of power and color Doppler sonography were compared in assessing fetal renal vasculature. Power Doppler sonography demonstrated diffuse "blush" in almost the entire cortex in 21 of 25 fetal kidneys, whereas it was demonstrated in half of the cortex in the other four kidneys. Color Doppler sonography failed to demonstrate a cortical blush in fetal kidneys. Power Doppler sonography has been shown to be superior to color Doppler sonography in the depiction of normal fetal intrarenal vasculature during pregnancy by demonstrating vascular blood flow better than color Doppler sonography.