To clarify intrarenal dynamic processes related to regional distribution in patients with unilateral renal disease, 2 radioactive tracers, 133Xe and 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) were introduced into a renal artery and intrarenal blood flow and urine flow aspects were observed by scintillation camera. Cortical blood flow decreased and medullary blood flow relatively increased with the advance of renal damage. Urine flow curve from normal cortex showed 2 phasic patterns. One early phase may correspond to the appearance of the tracer throught the proximal tubule and a 2 phase may correspond to the appearance of the tracer through the loop of Henle to the distal tubule. Under mannitol diuresis, 2 phasic urine flow curves from the cortex were obscured and the peak time of oelvic curve shifted to the earlier period. These studies were considered to be useful in evaluating unilateral renal function and may offer a good insight for intrarenal physiology concerning blood flow and urine flow.