The ultrasound pulsed Doppler flowmeter linked with the wide-angle phased array system was used to evaluate the renal blood flow in healthy subjects and in cases of renovascular and renal diseases from a transcutaneous approach. The renal arterial blood flow pattern in healthy subject was composed of a fast systolic forward flow followed by a gradually slowing diastolic flow continuing to enddiastole. The blood flow was detected in about 50% from the abdominal approach and in 100% from the dorsal approach in healthy subjects. In cases of renal artery stenosis, the acceleration time, i.e., the interval from the onset of upstroke to the peak of flow velocity, was prolonged and peak velocity was reduced, with worsening of stenosis. In cases of very severe stenosis, the turbulent flow was detected in the region of stenosis. The above mentioned abnormality of the flow pattern was also seen in cases of renal parenchymal damage, such as chronic glomerulonephritis, hydronephrosis and rejection phase of the implanted kidney.